fix(approvals): merge-time fixes for the watching badge (#473)

- session.ts: a pane capture that fails now CLEARS the watching label
  (and emits watchingChanged so pages drop the badge) instead of keeping
  the last one, so a failed capture degrades toward an alert rather than
  pre-acknowledging the next real idle prompt. Test updated; invariant
  noted in architecture-invariants.
- approvals-ui.js: the header bell counts only unacknowledged items
  (pendingApprovalsCount), matching codeman tui's pendingApprovalCount();
  pinned in watching-no-alert.test.ts.
- mobile-overview.js: move the orphaned "Pill copy per state" JSDoc back
  onto MOBILE_OVERVIEW_PILL_LABEL.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/web/public/mobile-overview.js

@@ -60,7 +60,6 @@ const MOBILE_OVERVIEW_RUN_MODES = [
   { mode: 'shell', label: 'Terminal / Shell', short: 'Shell' },
 ];
 
-/** Pill copy per state. Kept short: a phone row has ~90px for it. */
 /**
  * The one word every surface puts on the watching badge, and the tooltip that says
  * what the pane actually reported. Both live here so the phone overview, the desktop
@@ -69,6 +68,7 @@ const MOBILE_OVERVIEW_RUN_MODES = [
 const WATCHING_BADGE_TEXT = 'watching';
 const watchingBadgeTitle = (label) => 'Still running in the background: ' + label;
 
+/** Pill copy per state. Kept short: a phone row has ~90px for it. */
 const MOBILE_OVERVIEW_PILL_LABEL = {
   needs: 'needs you',
   error: 'error',