feat: choose your own pool account; skills with "token" in a doc name upload; System Health off Linux

- Skill snapshot/upload: a key file's name (.env, *.pem, id_rsa, .netrc,
  .credentials.json…) is always refused, but a word like token/secret/
  password/credential only in a data file's name — design-tokens.md or
  count_tokens.py is skill content, not a key.
- System Health: off Linux the History, CPU threads and Busiest processes
  cards (all read from /proc) are left out instead of shown empty; the CPU
  bar without a sample and Windows' always-zero Load row go too.
- Users pick their own pool account per tool (/api/me/pool-accounts,
  Settings → AI tools), within their groups, refused while pinned.
- Admin user detail, 9router update, session replay and Antigravity
  catalog changes from parallel sessions.

client/src/components/lanes/SessionReplay.tsx

@@ -10,7 +10,7 @@
  * second `--resume` (the server refuses one too, `ESESSIONLIVE`) — the typed
  * message is pasted there (never sent: Enter is the user's), with a toast; while
  * it is live the composer is off. Only Claude, Codex and a catalog tool with
- * `resumeById` (omp) can resume a session by id — any other tool's session
+ * `resumeById` (omp, Cursor, Antigravity) can resume a session by id — any other tool's session
  * offers a new session from the workspace home
  * instead. The header carries the transcript page's Resume/Fork
  * (`SessionResumeButton`, behind its warning). The session's tool and folder