feat(signals): add "Run with note" option to the scout Run now button #115210

Problem

On a scout's detail page, Run now dispatches a run with no steering. To point a one-off run at something ("check the checkout regression from this morning"), you have to leave a durable scout note. Every later scheduled run then reads that note too, until someone deletes it or it expires.

The backend already supports a note that applies to one run only. SignalScoutManualRunRequestSerializer.note is optional and capped at MAX_RUN_NOTE_CHARS (1,000). The MCP scout-run-now tool uses it. The UI never sends it.

Proposal

Add a dropdown side action to the Run now button in ScoutDetailHeader.tsx. It opens a "Run with note" option.

• Run now (main click) works the same as today and sends no body.
• Run with note opens a small dialog with:
  • A textarea with a live character count, capped at 1,000 to match the backend.
  • Helper copy: the note steers this run only. Later runs don't read it, but it stays in this run's history. It directs the scout's attention and doesn't force a finding.
  • A Run button that keeps the loading and disabled state the current button already has.
• Submitting calls signalsScoutConfigRun(teamId, configId, { note }).

Implementation notes

• scoutFleetLogic.runScoutNow takes an optional note and passes it through. The manualRunScoutIds loading state stays as it is.
• Use the LemonButton sideAction dropdown pattern (see ImplementButton.tsx).
• Permissions: a run with a note needs skill editor access, plus llm_skill:write on a scoped credential. Without it the endpoint returns 403. Disable the "Run with note" item with getAccessControlDisabledReason(AccessControlResourceType.LlmSkill, AccessControlLevel.Editor), as the Publish button already does. Plain Run now stays available.
• Analytics: keep actionType: 'run_now' and add extra: { has_note: boolean, note_length }, so we can tell how often people steer runs.
• Errors: no change. Budget and already-running errors still show the backend message in a toast.

Out of scope / follow-up

• Show run_note in the run history and run detail UI. It's stored in run metadata but not rendered yet, so a person can't see why a run looked at something.

Acceptance criteria

• Clicking Run now behaves exactly as before.
• Run with note dispatches a run with the note, and that run's metadata.run_note holds the note.
• Notes over 1,000 characters can't be submitted.
• Users without skill editor access see a disabled reason on Run with note, not a 403.
• The run_now event records whether a note was sent.