Address review findings: durability, stale container ids, honest toasts

An Opus review of the previous commit found several real gaps:

- pending_cleanup::save used plain write-temp-then-rename, unlike
  migration_store's fsync'd write it claimed to mirror — a crash in that
  window left a truncated record that list() would skip forever, silently
  reproducing the exact bug this module exists to fix. Now matches
  migration_store's File::create/write_all/sync_all/rename/sync_dir shape,
  and the tests exercise the real save/list/clear functions against a temp
  dir instead of re-implementing their bodies inline.
- remove_project and rebuild_project_container only ever looked at
  project.container_id, unlike every other container-destroying path in the
  codebase, which falls back to find_existing_container for exactly this
  race (a crash between creating a container and persisting its id). A miss
  here left a container that then blocked every subsequent volume removal
  with a 409, forever. Both now resolve the same way the rest of the
  codebase does, and record the container by its deterministic name rather
  than its id so a retry still has something that resolves.
- remove_project's toast promised an automatic retry unconditionally, even
  when writing the pending-cleanup record itself failed (the one case
  where nothing will actually retry). ProjectRemovalReport now carries
  retry_scheduled, and the UI is honest about which case it's in.
- remove_volumes_by_name now retries once after a short delay on a 409,
  since Docker releasing a volume's mount reference right after its
  container is removed is not always instantaneous, and this is exactly
  the sequence remove_project runs.
- rebuild_project_container (Reset) returns ProjectResetOutcome so the UI
  can warn when Reset could not fully clear a project's volumes, instead
  of only logging it — the new container silently reuses old data
  otherwise, which is what Reset promises not to do.
- retry_pending_cleanup_logged escalates a record's log level after it has
  failed for a week, since recorded_at was otherwise write-only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FGjXq6fqtAFHdbhk4f3PfZ

app/src/hooks/useProjects.ts

@@ -136,9 +136,9 @@ export function useProjects() {
   const rebuild = useCallback(
     (id: string) =>
       withOptimisticStatus(id, "starting", async () => {
-        const updated = await commands.rebuildProjectContainer(id);
-        updateProjectInList(updated);
-        return updated;
+        const outcome = await commands.rebuildProjectContainer(id);
+        updateProjectInList(outcome.project);
+        return outcome;
       }),
     [updateProjectInList, withOptimisticStatus],
   );