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/users/UserDetail.tsx

@@ -167,9 +167,11 @@ export function UserDetail({ userId }: { userId: number }) {
                       ·{" "}
                       {p.pin
                         ? t("detail.poolPinned", { account: p.pin })
-                        : p.group
-                          ? t("detail.poolGroup", { name: p.group.name })
-                          : t("detail.poolShared")}
+                        : p.choice
+                          ? t("detail.poolChosen", { account: p.choice })
+                          : p.group
+                            ? t("detail.poolGroup", { name: p.group.name })
+                            : t("detail.poolShared")}
                     </span>
                   </div>
                   {p.accounts.map((a) => {