fix(mesh): raise the connectivity cap 0.28 -> 0.42 on runtime evidence

Swept against the 46 capture-named Stage_S02 buffers with distinct assignment in
place: 0.28 anchors 40 exactly and leaves 4 unclaimed; 0.42 anchors 45 and leaves
none; nothing above 0.42 improves further, so it is the least permissive value
that captures the whole gain. 589 more resources decode, nothing is lost. The
cross-container consistency proxy worsens (46 -> 62) -- it cannot see a
systematic mis-anchor, and where the two disagree the capture wins. Suite green.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/sylpheed-formats/src/mesh.rs

@@ -779,13 +779,19 @@ pub fn debug_find_index_buffer(bytes: &[u8], name: &str, vb: usize) -> Vec<(usiz
 }
 
 /// The connectivity cap: a searched block whose mean triangle edge exceeds this
-/// fraction of its bounding-box diagonal is rejected. `0.28` is the shipped
-/// value. A runtime capture names blocks the engine really draws, and one of them
-/// (`e106_eng_02_l`, a 24-triangle LOD) measures **0.417** — so the cap has a
-/// known false positive. `XBG7_EDGE_CAP` overrides it for calibration sweeps;
-/// it is a diagnostic knob, not a setting (see docs/re/structures/xbg7-mesh.md).
+/// fraction of its bounding-box diagonal is rejected.
+///
+/// **0.42 since 2026-08-12**, raised from 0.28 on runtime evidence. A capture
+/// names the blocks the engine really draws, and the old cap rejected one of them
+/// outright — `e106_eng_02_l`, a 24-triangle LOD, measures **0.417**, because a
+/// coarse mesh's edges *are* a large fraction of its own size. Swept against the
+/// 46 capture-named `Stage_S02` buffers (with distinct anchor assignment): 0.28
+/// anchors 40 exactly and leaves 4 unclaimed, 0.42 anchors **45 and leaves none**,
+/// and nothing above 0.42 improves further — so this is the least permissive
+/// value that captures the whole measured gain. `XBG7_EDGE_CAP` overrides it (see
+/// docs/re/structures/xbg7-mesh.md).
 fn edge_cap() -> f32 {
-    std::env::var("XBG7_EDGE_CAP").ok().and_then(|v| v.parse().ok()).unwrap_or(0.28)
+    std::env::var("XBG7_EDGE_CAP").ok().and_then(|v| v.parse().ok()).unwrap_or(0.42)
 }
 
 /// Triangle count below which the looser [`small_cap`] applies. `0` (default)