docs: #101 — fix fabricated content in Recently closed entry

Code-review found four Important findings in the ISSUES.md entry
that landed in 381561f:
- broken relative link to the plan (../superpowers/... vs
  superpowers/...)
- wrong test class name (PhysicsDataCacheTests, the actual
  class is PhysicsDataCachePhantomSourceTests)
- wrong predicate description (referenced PhysicsRadius and
  vAabbR; the predicate only checks the high byte and the
  cached BSP root)
- fabricated method names (GameWindow.RegisterGfxObjShadow and
  ShadowShapeBuilder.FromGfxObj — neither exists)

This commit corrects all four. The verification evidence in
the entry was accurate and is preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/ISSUES.md

@@ -3480,20 +3480,21 @@ Unverified. The likely culprits, ranked by suspected probability:
 **Commits:** `f6305b1` — feat(physics): #101 — add IsPhantomGfxObjSource predicate; `5240d65` — fix(physics): #101 — suppress mesh-aabb-fallback for phantom GfxObj stabs; `6ca872f` — docs(test): #101 — sync stale GameWindow.cs line ref in test class doc
 **Component:** physics, dat-handling
 
-**Resolution.** `PhysicsDataCache.IsPhantomGfxObjSource(gfxObjId)` predicate returns `true` when a GfxObj
-has no PhysicsBSP (`PhysicsRadius == 0`) and the cyl/sphere shadow shapes would be synthesized
-from the visual AABB radius alone (`vAabbR > 0`). `GameWindow.RegisterGfxObjShadow` (line 6127)
-gates `ShadowShapeBuilder.FromGfxObj` behind this predicate — if the source is a phantom, the
-registration is skipped entirely. The 10 phantom stair cyls from `GfxObj 0x0100081A`
-(`vAabbR=0.82, hasPhys=False`) that previously blocked the player at the foot of the Holtburg
-upper-floor staircase are no longer registered. Collision falls through to entity `0x40B50089`
-(GfxObj `0x01000C16`, `hasPhys=True` BSP with walkable inclined polygon at `Normal.Z=0.717`,
-world ramp from (111.10, 25.50, 94.00)→(107.50, 27.10, 97.50)). 3 unit tests in
-`PhysicsDataCacheTests.IsPhantomGfxObjSource_*` (no BSP + AABB → true; has BSP → false;
-no BSP + no AABB → false) shipped alongside the predicate.
+**Resolution.** `PhysicsDataCache.IsPhantomGfxObjSource(gfxObjId)` predicate returns `true` when
+the entity's `SourceGfxObjOrSetupId` has the GfxObj high byte (`0x01`) AND no cached
+`GfxObjPhysics` entry exists (or its `BSP.Root` is null) — i.e., the underlying GfxObj had
+`HasPhysics=False` so `PhysicsDataCache.CacheGfxObj` short-circuited. The inline
+mesh-AABB-fallback gate at `GameWindow.cs:6127` checks this predicate and skips the shadow-shape
+registration entirely when the source is a phantom. The 10 phantom stair cyls from
+`GfxObj 0x0100081A` (`hasPhys=False`) that previously blocked the player at the foot of the
+Holtburg upper-floor staircase are no longer registered. Collision falls through to entity
+`0x40B50089` (GfxObj `0x01000C16`, `hasPhys=True` BSP with walkable inclined polygon at
+`Normal.Z=0.717`, world ramp from (111.10, 25.50, 94.00)→(107.50, 27.10, 97.50)). 3 unit tests
+in `PhysicsDataCachePhantomSourceTests.IsPhantomGfxObjSource_*` (no BSP → true; has BSP →
+false; non-GfxObj high byte → false) shipped alongside the predicate.
 
 **Investigation:** [`docs/research/2026-05-25-a6-stairs-cyl-retail-investigation.md`](research/2026-05-25-a6-stairs-cyl-retail-investigation.md).
-**Plan:** [`docs/superpowers/plans/2026-05-25-issue-101-stairs-cyl-phantom.md`](../superpowers/plans/2026-05-25-issue-101-stairs-cyl-phantom.md).
+**Plan:** [`docs/superpowers/plans/2026-05-25-issue-101-stairs-cyl-phantom.md`](superpowers/plans/2026-05-25-issue-101-stairs-cyl-phantom.md).
 
 **Verification.** Visual-verified at Holtburg upper-floor cottage stairs 2026-05-25 — `[cyl-test]`
 count on `obj=0x40B500*` post-fix = 0 (was 7101 pre-fix); `src=0x0100081A` mesh-aabb-fallback