file #131 (portal swirl gone through doorways) + #132 (candle flame vs aperture background) + the [outstage] capture probe

Two user reports from the #124 gate session, both axioms:
- #131: "the portal swirl is missing, when I look out from inside a
  house. Appears when I walk out again." Mechanism frame: under an
  interior root an outdoor dynamic's particles draw ONLY via the
  landscape slice's Scene pass (#118 outside-stage routing; #121
  excludes them from the last-pass particle callback) - if any link
  fails, the swirl draws nowhere exactly when indoors. Desk-exonerated
  already: filter key conventions uniform, the routing predicate
  correct, sphere from vertex bounds.
- #132: "I have a candle ... when a wall is behind it it shows, but if
  I turn a bit and the opening through a house is behind it candle
  light disappears." Background-dependent => per-pixel depth/blend at
  the aperture region, not owner culling. Possible overlap with the
  #124 look-in sub-pass (new pre-clear content in those pixels) - the
  pre-77cef4c check is in the issue.

Apparatus (env-gated, zero cost off): ACDREAM_PROBE_OUTSTAGE=1 ->
[outstage] per-slice outside-stage routing + cone verdict per dynamic
(print-on-change, RetailPViewRenderer) + [outstage-pt] slice
Scene-particle id set + live attached-emitter match count (GameWindow).
One capture standing inside looking at the portal pins which link
breaks.

Suites: App 259+1skip / Core 1439+2skip / UI 420 / Net 294 green.

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

src/AcDream.Core/Rendering/RenderingDiagnostics.cs

@@ -109,6 +109,20 @@ public static class RenderingDiagnostics
     public static bool ProbeViewerEnabled { get; set; } =
         Environment.GetEnvironmentVariable("ACDREAM_PROBE_VIEWER") == "1";
 
+    /// <summary>
+    /// #131 (2026-06-12) outside-stage dynamics probe. When true, the renderer
+    /// emits one <c>[outstage]</c> line per CHANGE of the outside-stage
+    /// routing + per-slice cone verdict set under an interior root (which
+    /// outdoor dynamics were routed to the landscape slice, which survived the
+    /// slice viewcone), and GameWindow emits one <c>[outstage-pt]</c> line per
+    /// change of the slice Scene-particle id set + matched-emitter count.
+    /// Built for the portal-swirl-missing-through-doorway capture. Light:
+    /// silent while the set is stable. Initial state from
+    /// <c>ACDREAM_PROBE_OUTSTAGE=1</c>.
+    /// </summary>
+    public static bool ProbeOutStageEnabled { get; set; } =
+        Environment.GetEnvironmentVariable("ACDREAM_PROBE_OUTSTAGE") == "1";
+
     /// <summary>
     /// Phase U.4c (2026-05-31) flap-convergence probe. When true, the portal
     /// visibility pass emits, EVERY frame the camera root is an indoor cell, a