feat(D.5.3a): selected-object meter — Health bar + name on the action bar

Port of gmToolbarUI::HandleSelectionChanged (acclient_2013_pseudo_c.txt:198635).
When the player selects a world object the action bar's bottom strip shows the
object name + (for player/pet/attackable targets) a live Health meter; deselect
clears it. Mana (#140) + stack slider deferred.

- SelectedObjectController (new): clear-then-populate on selection change; sets
  name (UiText child, VitalsController pattern), overlay state (ObjectSelected /
  StackedItemSelected via UiDatElement.ActiveState), shows the health meter and
  sends QueryHealth for health targets. Subscribes via a delegate seam (no
  GameWindow coupling).
- GameWindow: _selectedGuid field -> SelectedGuid property + SelectionChanged
  event (fires on actual change only); 3 write sites converted, reads untouched.
  All selection-write paths (LMB pick, Tab/Q, despawn-clear via Tick()) run on
  the render thread, so the event-driven UI mutation is single-threaded.
- WorldSession.SendQueryHealth (0x01BF) — wraps SocialActions.BuildQueryHealth.
- DatWidgetFactory.BuildMeter: handle the single-image toolbar meter shape
  (back-track on the element's own DirectState, fill on one Type-3 child). The
  sprites go in the TILE slot (DrawMode=Normal tiles to full bar geometry per
  UIElement_Meter::DrawChildren) — a left-cap assignment would gap/clamp a
  sub-140px sprite. Vitals 3-slice path unchanged.
- ToolbarController.HiddenIds: A1 (health) now owned by SelectedObjectController;
  A2 (mana) + A4 (stack) stay hidden (deferred) so their dat back-tracks don't
  render as stray empty bars.

Adversarial Opus review found + fixed: the mana-meter orphan (A2 left unhidden)
and the meter tile-vs-cap render bug (C1). Divergence rows AP-46 (health gate
approximation: IsLiveCreatureTarget vs IsPlayer||pet||attackable) + AP-47
(meter shown on select vs on UpdateHealth reply). Spec §5 corrected.

Build + full test suite green (2,684 passed / 4 skipped). Health meter render
fidelity (full-width fill + fraction mapping) pending the user's visual gate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/ISSUES.md

@@ -48,7 +48,7 @@ Copy this block when adding a new issue:
 
 ## #140 — Toolbar interactivity — selected-object display
 
-**Status:** OPEN
+**Status:** IN PROGRESS (D.5.3a — health + name landed, pending visual gate; mana + stack slider still deferred)
 **Severity:** MEDIUM
 **Filed:** 2026-06-17
 **Component:** ui — D.5 toolbar / selection
@@ -56,6 +56,7 @@ Copy this block when adding a new issue:
 **Description:** The action bar (D.5.1) is the retail "selected object" display. Wire the B.4 WorldPicker/selection state to the toolbar's currently-hidden elements: the two meters 0x100001A1 (selected-object Health) / 0x100001A2 (selected-object Mana) + the stack slider 0x100001A4 + the object-name line, so the bar shows what the player has selected in the world. Click-to-use + the peace/war stance indicator already shipped in D.5.1. Promote to roadmap D.5.3 (already listed there).
 
 **Root cause / status:** The selection-state wire was deferred out of D.5.1 scope; the meter/slider elements are present in LayoutDesc 0x21000016 but hidden (no backing data). D.5.3 is the planned port.
+- **D.5.3a (2026-06-18):** the Health meter (0x100001A1) + the object-name line (0x1000019F) + the overlay state (0x100001A0) are wired via `SelectedObjectController` (port of `gmToolbarUI::HandleSelectionChanged`); `SelectionChanged` event on `GameWindow`; `QueryHealth (0x01BF)` sent on select. Spec/plan: `docs/superpowers/specs|plans/2026-06-18-d53a-*`. **Still deferred:** the Mana meter (0x100001A2 — owned-item-only; no remote-target mana path yet) and the stack entry/slider (0x100001A3/A4 — stack-split UI). Divergence rows AP-46/AP-47. Awaiting the visual gate before closing the health half.
 
 **Files:** `src/AcDream.App/UI/Layout/ToolbarController.cs` + the selection/WorldPicker state (see `claude-memory/project_interaction_pipeline.md`).