probe: ACDREAM_PROBE_REVEAL_TIMING — wall-clock attribution of the login/portal hold

[reveal-timing] lines from the reveal coordinator: per-dimension
first-ready edges (render neighborhood, composite textures, collision,
gate, materialization), 1 Hz progress with the resident-landblock count
(new GpuWorldState.LoadedLandblockCount), and one SUMMARY line at the
viewport reveal. Measurement-first groundwork for the login-load speedup:
the readiness barrier observes its dimensions serially, so the edges give
each dimension's observed tail while the progress lines expose the
pacing shape (a budget-paced linear drip reads directly off the counts).
Probe-gated in StreamingDiagnostics per Code Structure Rules §5; no
behavior change, one branch per Evaluate poll when unset.

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

src/AcDream.App/Composition/SessionPlayerComposition.cs

@@ -425,7 +425,8 @@ internal sealed class SessionPlayerCompositionPhase
             spawnClaimClassifier.IsUnhydratable,
             worldQuiescence,
             streaming,
-            revealRenderResources);
+            revealRenderResources,
+            () => live.WorldState.LoadedLandblockCount);
         Fault(SessionPlayerCompositionPoint.WorldRevealCreated);
 
         return CompleteSessionPlayer(