fix(tabs): re-evaluate auto-wrap on resize and on every full tab rebuild

Review polish on the desktop tab auto-wrap:

- Auto-wrap is purely width-driven, but updateTabOverflowMode() was only called at the
  tail of _renderSessionTabsImmediate (SSE content renders). Window resize — the primary
  trigger for tabs crossing the one-row overflow threshold — never re-evaluated it, so
  narrowing/widening the window left the wrap state stale until an unrelated status event
  fired a render. Call it from the debounced window-resize handler (no-op on
  mobile/tablet, where the method bails).

- Move the re-evaluation into _fullRenderSessionTabs() as well, so the incremental
  branch's two early `_fullRenderSessionTabs(); return;` paths (badge add/remove, which
  change tab width) and the manual two-rows toggle (applyTabWrapSettings → _fullRender…)
  re-evaluate too. The latter also fixes a transient where enabling manual two-rows while
  auto-wrap was on left both classes set (clipping folder tabs to 96px) until the next
  render.

- Add boundary cases to the policy test: exact fit and the +1 sub-pixel tolerance (no
  wrap), 2px over (wrap), and a single overflowing tab (no wrap).

Verified: tab-overflow test passes; tsc, check:frontend-syntax, check:public-assets,
prettier all clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/public/app.js

@@ -2765,6 +2765,12 @@ class CodemanApp {
 
     // Update connection lines after tabs change (positions may have shifted)
     this.updateConnectionLines();
+
+    // Re-evaluate desktop auto-wrap for every full rebuild, including the incremental
+    // branch's early `_fullRenderSessionTabs(); return;` paths and the manual two-rows
+    // toggle (applyTabWrapSettings calls this) which would otherwise leave a stale
+    // tabs-auto-wrap class until the next content render.
+    this.updateTabOverflowMode();
   }
 
   // Set up arrow key navigation for session tabs (accessibility)