The terminal's resilience screen takes a snapshot now with `n` and brings the mirror level with `l`, after a confirm, as MCP `snapshot_now` and `mirror_now` do #7318

Intent: a forge admin can take a backup right now from the terminal, without opening the page.

Done:

• [ ] On the resilience screen (src/tui/screens/resilience.ts), n asks take a snapshot now? y/n; y calls the same src/snapshot/service.ts function the MCP tool snapshot_now uses, then the screen re-reads and the newest snapshot shows on top.
• [ ] l asks bring the mirror level now? y/n; y calls the function mirror_now uses and says in words whether it reached the mirror. No key or secret is ever drawn.
• [ ] A viewer who is not a forge admin is not offered either key, and gets the action's refusal if they press it.
• [ ] A test in test/tui-resilience.test.ts (or a new file beside it) proves n adds a snapshot and that a non-admin is refused.

Files: src/tui/screens/resilience.ts, a test. Risk: #7269, #7276 and #7297 also edit this screen; use n and l, which they do not take.