Harden the seams a project sweep surfaced

A systematic review of the whole codebase (main process, renderer,
IPC/migration/packaging seams) surfaced four real defects; each is
fixed at its root:

- Legacy catalogue drift: the operator's profile still carried 89
  active skills from the removed ~/.agents import era next to the 228
  built-ins. Catalogue sync now mirrors the bundle - actives whose slug
  the bundle does not ship retire (bindings keep resolving via their
  pinned revisions; retired skills leave list_skills and cannot be
  granted anew)
- Broken-bundle guard: staging now refuses a bundle without the
  humanizer skill, so an empty or quarantined resources folder can
  never trigger the mirror pass into retiring a healthy catalogue
- Duplicate agent names: @mentions, DM routing, and task assignment all
  resolve by name, so createAgent and updateAgent renames now reject a
  name already held by an active agent (case-insensitive); the mention
  resolver still refuses to guess between legacy duplicates
- Stale DM titles: agent-to-agent conversation rows titled themselves
  from the frozen creation-time space name, so renames never reached
  the sidebar; direct titles now derive from members' current names

Verified clean in the same sweep: IPC surface (82 channels, handler +
preload + api aligned), per-migration transactions with rollback,
quota-parking month rollover, retry-budget counting, meeting spot
reuse across floor-plan rebuilds.

src/main/index.ts

@@ -100,8 +100,8 @@ function syncAllOrganizationSkills(connection: DatabaseConnection, artifactRoot:
     const orgs = connection.db.prepare("select id from organizations").all() as Array<{ id: string }>;
     for (const org of orgs) {
       const report = connection.transaction(() => importStagedSkills(skills, org.id, staged));
-      if (report.imported > 0 || report.failures.length > 0) {
-        console.info(`[skills] org ${org.id}: imported ${report.imported}, skipped ${report.skipped}, failures ${report.failures.length}`);
+      if (report.imported > 0 || report.retired > 0 || report.failures.length > 0) {
+        console.info(`[skills] org ${org.id}: imported ${report.imported}, skipped ${report.skipped}, retired ${report.retired}, failures ${report.failures.length}`);
         for (const failure of report.failures.slice(0, 5)) console.warn(`[skills] ${failure}`);
       }
     }