feat(chargen): Campaign CC slice CC6b-PRE — idle loop, rotation, zoom (mount-independent half)

Idle animation loop: decomp re-read of gmCGAppearancePage::Update's trailing
StartAnimation/StopAnimation gate (~0x0047EF01-0x0047EF12) plus the ctor
evidence that m_bZoomedIn is a decompiler-elided bool (never explicitly set
away from its zero default, unlike its two sibling bools) establishes that
retail's chargen preview defaults to the idle loop PLAYING, not the frozen
rest pose CC6a shipped as a deliberate simplification (TS-83) — the rest pose
only appears once Zoom In fires. New Core primitive
RetailAnimationCyclePlayback ports CPhysicsObj::set_sequence_animation's
advance-with-wrap + lerp/slerp effect (the same algorithm
LiveEntityAnimationPresenter's legacy NPC-idle branch already carries inline;
not consolidated this round — out of blast radius for a preview-only
feature, noted in the new type's own doc). New ChargenPreviewAnimator drives
the per-tick swap; ChargenPreviewEntityBuilder gained TryBuildAnimated
alongside the byte-behavior-unchanged TryBuild. Olthoi/OlthoiAcid use the
SAME enum key for idle and rest DIDs (decomp-confirmed quirk). TS-83 retired
in the register (§4 count 50->49).

Rotation controller: ChargenPreviewRotationController ports
Rotate/DoRotation (0x0047CB50/0x0047CA80) verbatim — toggle-to-stop,
deltaDegrees = ((now-last)/RotationSecondsPerRevolution)*360, single-pass
+-360 clamp (not a full modulo, matching retail's own tail), the -1.0
invalidation sentinel. Applies to the entity's heading via the existing
MoveToMath.SetHeading port, not the camera, confirming CC6a's own note.

Zoom tween: ChargenPreviewZoomController ports ZoomIn/ZoomOut/
DoZoomAnimation (0x0047CF00/0x0047D050/0x0047C960) — a LINEAR 0.6s tween
(no easing curve in the decomp) between the already-recorded camera eye
profiles, calling into the animator's zoom swap IMMEDIATELY at button-press
time, matching retail's call order exactly.

m_alternateSetupID (research correction): re-reading the decomp
function-by-function found all five m_alternateSetupID write sites —
including the two the CC6a review cited — belong to gmBarberUI (the
post-creation barber shop), not gmCGAppearancePage, which has no
m_pOption1Checkbox-equivalent field and never writes the field. For
character creation the field is always INVALID_DID in retail. TryCompose
still gained a real, decomp-cited alternateSetupIdOverride parameter
(default no-op) implementing gmCG3DView::Update's generic override
precedence, for a future non-chargen consumer.

RetailHeldPose extraction: shared ResolvePoseDid/ComposePartTransform
between RetailPaperdollPoseApplicator and ChargenPreviewEntityBuilder — a
clean mechanical extraction, behavior-identical on the paperdoll side.

Bookkeeping: CC6a ledger row now cites its real commit SHAs (55bfd9ca,
1774d8b2); new CC6b-PRE ledger row records scope done + the page-mount half
still owed.

Tests: RetailAnimationCyclePlaybackTests (10, Core), ChargenAppearanceFactoryTests
(+4), ChargenPreviewRotationControllerTests (9), ChargenPreviewZoomControllerTests
(7), ChargenPreviewAnimatorTests (7, hand-built fixtures), ChargenPreviewEntityBuilderTests
(+5, installed-DAT). Core.Tests 4786/1 skip, Content.Tests 147/0, App.Tests
5149/6 skips — zero failures, full solution Release build green. One
pre-existing, unrelated flake noted: Core.Net.Tests' NakEmissionTests loss
soak failed once in the full-suite run, passed 1/1 isolated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.App/Rendering/ChargenPreviewZoomController.cs

@@ -0,0 +1,135 @@
+using System.Numerics;
+
+namespace AcDream.App.Rendering;
+
+/// <summary>
+/// Presentation-free port of <c>gmCGAppearancePage::ZoomIn</c>/<c>ZoomOut</c>
+/// (<c>0x0047CF00</c>/<c>0x0047D050</c>) and <c>DoZoomAnimation</c>
+/// (<c>0x0047C960</c>): a linear 0.6s tween of the preview camera's eye
+/// between <see cref="ChargenPreviewCamera.ResolveDefaultEye"/> (zoomed IN)
+/// and <see cref="ChargenPreviewCamera.ResolveZoomedOutEye"/> (zoomed OUT),
+/// driving the SAME <see cref="ChargenPreviewAnimator"/> zoom-state swap the
+/// button presses trigger in retail — immediately, not once the tween
+/// finishes (see <see cref="ChargenPreviewAnimator"/>'s own doc comment).
+///
+/// <para>
+/// Retail drives <see cref="Tick"/> once per frame from a global-message-3
+/// tick while <c>m_bShouldZoomAnimate</c> is set
+/// (<c>gmCGAppearancePage::ListenToGlobalMessage @ 0x0047CED0</c>); the
+/// CC6b page-mount half will bind the Zoom In/Out buttons to
+/// <see cref="ZoomIn"/>/<see cref="ZoomOut"/> and the render loop to
+/// <see cref="Tick"/>. Direction is always <c>(0,0,0)</c> for this camera
+/// (see <see cref="ChargenPreviewCamera"/>'s own remarks), so only the eye
+/// position tweens — retail's own <c>m_vectCurDirection</c> lerp is a no-op
+/// here and is not reproduced.
+/// </para>
+/// </summary>
+internal sealed class ChargenPreviewZoomController
+{
+    /// <summary>
+    /// <c>ZoomIn</c>/<c>ZoomOut</c>'s explicit invalidation write
+    /// (<c>this->m_dAnimDuration = -0.1</c>, pseudo-C ~0x0047cff1/0x0047cffb
+    /// and ~0x0047d12c/0x0047d136 — the exact IEEE-754 bit pattern for
+    /// <c>-0.1</c>) so the very next <see cref="Tick"/> resets the duration
+    /// to <see cref="ChargenPreviewCamera.ZoomTweenDurationSeconds"/> and the
+    /// start time to "now", matching <c>DoZoomAnimation</c>'s own
+    /// reset-if-invalid guard exactly.
+    /// </summary>
+    private const double InvalidDurationSentinel = -0.1;
+
+    private readonly uint _heritageId;
+    private Vector3 _startEye;
+    private Vector3 _targetEye;
+    private double _animStartTime;
+    private double _animDuration;
+    private bool _shouldAnimate;
+    private bool _zoomedIn;
+
+    public ChargenPreviewZoomController(uint heritageId, ChargenPreviewCamera camera)
+    {
+        ArgumentNullException.ThrowIfNull(camera);
+        _heritageId = heritageId;
+        Camera = camera;
+    }
+
+    public ChargenPreviewCamera Camera { get; }
+
+    /// <summary>Mirrors retail's <c>m_bZoomedIn</c> — false (not zoomed in)
+    /// is the ctor-implicit default, matching <see cref="ChargenPreviewAnimator"/>'s
+    /// own default (see that class's doc comment for the shared citation).</summary>
+    public bool IsZoomedIn => _zoomedIn;
+
+    /// <summary>
+    /// <c>gmCGAppearancePage::ZoomIn @ 0x0047CF00</c>: no-op if already
+    /// zoomed in (retail's own early-return guard). Otherwise starts a tween
+    /// from the camera's CURRENT eye to the default (zoomed-IN) per-heritage
+    /// profile and swaps <paramref name="animator"/> to the frozen rest
+    /// pose IMMEDIATELY (<c>gmCG3DView::StopAnimation</c>'s call site,
+    /// pseudo-C ~0x0047d024, precedes the tween's own completion by
+    /// definition — it runs once, synchronously, inside <c>ZoomIn</c>
+    /// itself).
+    /// </summary>
+    public void ZoomIn(ChargenPreviewAnimator? animator)
+    {
+        if (_zoomedIn)
+            return;
+        StartTween(ChargenPreviewCamera.ResolveDefaultEye(_heritageId));
+        _zoomedIn = true;
+        animator?.SetZoomedIn(true);
+    }
+
+    /// <summary>
+    /// <c>gmCGAppearancePage::ZoomOut @ 0x0047D050</c>: no-op if not
+    /// currently zoomed in. Otherwise starts a tween toward the zoomed-OUT
+    /// per-heritage profile and swaps <paramref name="animator"/> back to
+    /// the playing idle loop immediately, mirroring <see cref="ZoomIn"/>.
+    /// </summary>
+    public void ZoomOut(ChargenPreviewAnimator? animator)
+    {
+        if (!_zoomedIn)
+            return;
+        StartTween(ChargenPreviewCamera.ResolveZoomedOutEye(_heritageId));
+        _zoomedIn = false;
+        animator?.SetZoomedIn(false);
+    }
+
+    private void StartTween(Vector3 targetEye)
+    {
+        _startEye = Camera.Eye;
+        _targetEye = targetEye;
+        _shouldAnimate = true;
+        _animDuration = InvalidDurationSentinel;
+    }
+
+    /// <summary>
+    /// <c>gmCGAppearancePage::DoZoomAnimation @ 0x0047C960</c>: a LINEAR
+    /// (not eased) lerp of the eye position from <c>m_vectStartPosition</c>
+    /// to <c>m_vectTargPosition</c> over
+    /// <see cref="ChargenPreviewCamera.ZoomTweenDurationSeconds"/>, clamping
+    /// <c>t</c> to exactly 1.0 (and clearing <c>m_bShouldZoomAnimate</c>) the
+    /// tick that reaches or passes the duration — the decomp shows a
+    /// straight <c>(targ - start) * t + start</c> per axis with no easing
+    /// curve applied anywhere in this function.
+    /// </summary>
+    public void Tick(double now)
+    {
+        if (!_shouldAnimate)
+            return;
+
+        if (_animDuration <= 0d)
+        {
+            _animDuration = ChargenPreviewCamera.ZoomTweenDurationSeconds;
+            _animStartTime = now;
+        }
+
+        double elapsed = now - _animStartTime;
+        if (elapsed >= _animDuration)
+        {
+            _shouldAnimate = false;
+            elapsed = _animDuration;
+        }
+
+        float t = (float)(elapsed / _animDuration);
+        Camera.Eye = Vector3.Lerp(_startEye, _targetEye, t);
+    }
+}