fix(measure): ask the primordial law the right question

Three defects, two of them mine.

1. The anchor was a guess. LargestComponentAnchor() returned a hardcoded
   point near the (0,0) spine and the comment admitted it, so
   NOT_CONNECTED meant "not connected to a guessed point". The flood fill
   already knows the answer; it now returns LargestComponentPoint (tie-
   broken by lowest cell index, so it stays deterministic),
   LargestComponentCells and NumComponentsAtLeast1Pct.

2. "Connected to the largest component" is NOT the primordial law. The
   law is that a player must not descend into a place they cannot leave
   -- a question about MOUTHS. A strate can be 57 disconnected shafts and
   be fine, provided the shaft you arrive in is the shaft you leave from.
   The test now asks arrival -> departure per strate: the LowerPoint of
   the passage arriving, to the UpperPoint of the passage departing.

3. A false verdict and a true one were indistinguishable. VF_AreConnected
   returned false both when no route existed and when the endpoint's own
   coarse cell sampled solid -- and a passage mouth is a carved tube whose
   cell centre lands in adjacent rock easily. It now returns
   EVoxelConnectivityResult and snaps to an adjacent air cell first,
   reporting the repair.

RESULT: the earlier "5 of 15 endpoints disconnected" was an ARTIFACT of
the guessed anchor plus the wrong question. Corrected: 13 of 15 connected,
0 StartCellSolid, 0 GoalCellSolid.

One real finding survives. arrival -> departure passes for 5 of 6
applicable strates; VerticalShafts FAILS -- its arrival mouth is in the
largest component, its departure mouth is not. NOT yet reported as a bug:
a coarse grid can falsely SEPARATE as well as falsely join, and a
connecting corridor thinner than SampleStep vanishes. Next task settles
it at a finer step.

Also noted: GetPassages() contains a self-referential surface entry
(0 -> 0), excluded from the chain law.

Build clean, 18 succeeded / 0 warnings / 0 failed, verified in VoxelM.log.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bp7FxoQcSoiuhxjuLr6aBM

CODEMAP.md

@@ -307,15 +307,18 @@ Headless, read-only Tier 2 measurement pass. `VF_MeasureStrate` samples one stra
 boundary-seal-derived (or explicitly overridden) interior margin into a bounded coarse grid,
 performs one deterministic 6-connected air flood fill, and derives fractions, components,
 walkability, feature scale, and clearance from that grid. Metrics report the resolved margin and
-the inclusive/exclusive voxel Z window used.
+the inclusive/exclusive voxel Z window used, plus the largest component's deterministic lowest-cell
+representative point, cell count, and count of components holding at least 1% of the air.
 `VF_AreConnected` recovers a deterministic BFS parent path from the same kind of grid and checks
-only that route at full voxel resolution before returning true; a coarse false positive sets
-`bOutCoarseLied`. No UObject state, cache, actor, world, or PIE is required.
+only that route at full voxel resolution before returning `Connected`. It returns an explicit
+`EVoxelConnectivityResult`; a solid endpoint cell is repaired by snapping to the nearest air cell
+among its 26 neighbours when possible, and reports the snap through its out flags. No UObject state,
+cache, actor, world, or PIE is required.
 | Symbol | Role |
 |--------|------|
-| `FVoxelStrateMeasureSettings` / `FVoxelStrateMetrics` | Plain settings/result structs for bounded strate sampling and derived measurements; callers may override the interior margin, and results identify the resolved margin/Z window. |
+| `FVoxelStrateMeasureSettings` / `FVoxelStrateMetrics` | Plain settings/result structs for bounded strate sampling and derived measurements; callers may override the interior margin, and results identify the resolved margin/Z window and deterministic component representatives. |
 | `VF_MeasureStrate` | One-grid/one-flood-fill strate metrics; refuses invalid bounds or a grid over `MaxCells`. |
-| `VF_AreConnected` | Coarse 6-connected BFS plus one full-resolution recheck of its recovered route. |
+| `VF_AreConnected` | Coarse 6-connected BFS plus one full-resolution recheck of its recovered route, with explicit endpoint-solid, out-of-window, coarse-lie, and connectivity outcomes. |
 
 ### 3.7 Cave morphology (SDF rooms/tunnels) — `Public/VoxelCaveMorphology.h` + `.cpp`
 Header is rich with inline docs. Two namespaces + a per-chunk cache system.