feat(physics): port retail projectile integration

Add a pure Core projectile driver for retail clock quanta, final-state acceleration, 50-unit velocity clamping, world-space angular integration, full-3D AlignPath, and oriented Setup-local sphere sweeps. Preserve exact success versus set_frame-only failure semantics, independent Contact/OnWalkable state, and full-cell identity across all landblock directions.

Port OBJECTINFO::missile_ignore with explicit weenie/creature metadata, remove the invented transition-step cap, retain PathClipped without arming PerfectClip, and keep authoritative target identity optional. Add malformed-shape/clock, thin-wall, terrain, target-exclusion, frame-spike, failure-state, and boundary conformance coverage.

Retire TS-2 and synchronize the architecture, milestones, roadmap, research oracle, and durable physics memory.

Co-Authored-By: Codex <noreply@openai.com>

docs/research/2026-07-13-retail-projectile-vfx-pseudocode.md

@@ -821,3 +821,54 @@ observable ordering without exposing a half-committed pose to modern sinks.
   through normal owner teardown while retaining DAT-static/synthetic poses.
   TS-11 and TS-12 are retired with the emitter-binding and
   live-part mechanisms.
+
+## 15. Step 6 implementation map (2026-07-14)
+
+- `ProjectilePhysicsStepper` is a pure Core clock/integration/sweep owner. It
+  accepts an already-live `PhysicsBody`, full cell, Setup-local sphere, local
+  entity identity, and optional authoritative target identity; it owns no
+  renderer, network state, or logical lifetime. `ProjectileController` in the
+  next step will select records and apply authoritative corrections around it.
+- The shared integrator now uses retail's 0.2-second maximum catch-up quantum
+  and world-space angular rotation (`Frame::grotate`, quaternion delta
+  pre-multiplied). Velocity is clamped to 50 world units/second before
+  integration, acceleration is recalculated from the final PhysicsState each
+  quantum, and AlignPath replaces orientation from the complete three-axis
+  displacement through `RetailFrameMath.SetVectorHeading`.
+- Installed projectile Setup auditing proves the required arrow, bolt, and
+  representative spell set uses exactly one ordinary collision sphere. The
+  port retains the complete Setup-local origin and scales both origin and
+  radius; it therefore preserves Force Bolt's offset
+  `(0, -0.165, 0.1045)` and never derives collision size from the mesh.
+- `ResolveWithTransition` accepts the sphere's local origin and begin/end
+  orientations, carries the resulting orientation in `ResolveResult`, skips
+  the moving entity's own shadow, and automatically adds PathClipped for a
+  Missile body. It deliberately does not add PerfectClip.
+- `ObjectInfo.MissileIgnore` is the exact `0x0050CEB0` branch tree. Runtime
+  collision metadata now distinguishes “has a CWeenieObject” from “is a
+  creature”; server-created live entities set the former, while DAT landblock
+  geometry does not. The designated target remains zero until an
+  authoritative wire/runtime source supplies one.
+- Transition subdivision provides the continuous sweep. Conformance covers
+  maximum-speed thin sphere and BSP walls, terrain floors, elastic reflection,
+  inelastic stopping, missiles, ethereal weenies, designated and unknown
+  creature targets, self exclusion, and loaded landblock crossing. Retail's
+  transition loop has no arbitrary step-count cap; a 50-unit/second arrow with
+  a 0.1-unit sphere therefore completes all 100 sweep steps in one 0.2-second
+  catch-up quantum. On transition failure, the integrated candidate frame is
+  retained in the current cell and cached velocity is zeroed without running
+  `SetPositionInternal` or collision response; transition-local contact,
+  stationary, walkable-polygon, and sliding results are discarded. Successful
+  `SetPositionInternal` writeback keeps Contact distinct from OnWalkable: a
+  steep plane can be contact while only normals with Z at or above FloorZ are
+  walkable. Both facts commit before collision response, so a floor impact
+  settles on the following tick without turning a steep hit into ground.
+- The landblock-crossing test exposed and fixed a shared world-frame rebasing
+  defect: after the containing cell crosses a 192-metre block boundary, the
+  carried block origin must move by the same block delta before the next
+  substep. Retail gets this for free from cell-relative `Position.Frame`;
+  acdream now performs the equivalent rebase at the ordered containing-cell
+  retarget, preventing one extra landblock jump per remaining sweep substep.
+  Boundary conformance covers positive and negative X and Y crossings.
+- TS-2 is retired. AP-83 and AP-91 remain because ordinary missiles are
+  PathClipped and do not arm their dormant PerfectClip time-of-impact paths.