T6 (BR-7) C4: straddle-only outside-add (A6.P5 widening DELETED) + #90 stickiness removed

The two remaining flagged workarounds retired, per the BR-7 plan +
the WF1 [MEDIUM] correction (re-gate, do NOT delete the outside-add):

1. A6.P5 hasExitPortal topology widening DELETED. Outdoor cells enter the
   collision cell array ONLY on the retail straddle gate - |dist| <
   radius + F_EPSILON against an exterior portal plane
   (CEnvCell::find_transit_cells Ghidra 0x0052c820, gate 0052c9d6,
   live-binary verified) - the same flag that already gated the
   membership pick (#112 rider). The widening existed so outdoor-
   registered doors stayed findable from indoor cells under the old flat
   registry query; with per-cell shadow lists the door is found in the
   straddle-admitted outdoor cell's own list (tick-13558 pin holds).
   The hasExitPortal out-param + plumbing deleted from
   FindTransitCellsSphere; the AddAllOutsideCells call in
   BuildCellSetAndPickContaining re-gated on exitOutsideStraddle
   (once-per-walk = retail CELLARRAY.added_outside).

2. #90 ResolveCellId sphere-overlap stickiness REMOVED (the 4ca3596
   workaround, deferred-to-A6.P4 in the physics digest). It was dead
   code: the method's only caller is FindEnvCollisions' cache-null TEST
   fallback, and the indoor branch (where the stickiness lived) required
   a non-null DataCache. Production membership flows exclusively through
   the collide-then-pick advance whose ordered-array hysteresis (current
   cell at index 0, interior-wins-break) is the retail mechanism the
   workaround approximated. ResolveCellId reduced to the bare
   prefix-preserving outdoor re-derive, documented test-only.

Test updates (pins of the deleted behaviors inverted to retail):
- A6P5_BuildCellSetFromIndoorStart_ReachesDoorOutdoorCell (asserted the
  topology widening verbatim) -> DeepInteriorSphere_NoStraddle_
  AddsNoOutdoorCells: a deep-interior sphere admits NO outdoor cells.
- A6P5_BuildCellSetFromAlcove... -> AlcoveSphere_StraddlesExitPortal_
  ReachesDoorOutdoorCell (the captured alcove position genuinely
  straddles - the retail-positive half).
- Issue112MembershipTests straddle pin + the second-sphere straddle test
  updated to the single-flag signature.

Suites: Core 1416/0/2, App 225, UI 420, Net 294 - green.

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

tests/AcDream.Core.Tests/Conformance/Issue112MembershipTests.cs

@@ -101,21 +101,22 @@ public sealed class Issue112MembershipTests
         var cell102 = cache.GetCellStruct(0xA9B30102u)!;
 
         // (a) Deep inside the room, 3 m from the door plane: the cell HAS an
-        //     exterior portal (topology flag) but no straddle → no outdoor
-        //     admission flag (retail: var_44 stays 0, add_all_outside skipped).
+        //     exterior portal but no straddle → no outdoor admission flag
+        //     (retail: var_44 stays 0, add_all_outside skipped). (BR-7 C4
+        //     deleted the non-retail hasExitPortal topology output — the
+        //     straddle flag is the only outdoor-admission signal, like
+        //     retail.)
         var farCandidates = new List<uint>();
         CellTransit.FindTransitCellsSphere(
             cache, cell102, 0xA9B30102u, new Vector3(183.0f, 86.5f, 117.0f),
-            FootRadius, farCandidates, out bool farStraddle, out bool farHasExit);
-        Assert.True(farHasExit);
+            FootRadius, farCandidates, out bool farStraddle);
         Assert.False(farStraddle);
 
         // (b) At the door plane (0.30 m away < 0.48 radius): straddle fires.
         var nearCandidates = new List<uint>();
         CellTransit.FindTransitCellsSphere(
             cache, cell102, 0xA9B30102u, new Vector3(185.70f, 85.5f, 117.0f),
-            FootRadius, nearCandidates, out bool nearStraddle, out bool nearHasExit);
-        Assert.True(nearHasExit);
+            FootRadius, nearCandidates, out bool nearStraddle);
         Assert.True(nearStraddle);
     }