"Now" says nothing while the app is plainly coming alive #168

Pushed.

While production is deploying and no agent run is going, "Now"'s empty state now reads "Production is coming up — the log above has it." instead of "Nothing yet. Tell the crew something." I chose the empty-state text over adding a row: a redeploy row in Now would clutter the crew's own work list with background machine noise (the issue's own risk callout), and the head card already carries the one live tail for the deploy, so the text just points back at it rather than opening a second stream. With no deploy and no agent run, Now is byte-for-byte what it was before.

Changed:

• src/web/studio/app.ts: the Now panel's empty state branches on deployTailing (already computed by appPanels).
• src/web/studio/previews.ts: fixed the comment at deployTail that claimed a running deploy was "already what 'Now' shows" — it wasn't; now it describes the actual empty-state pointer.
• test/studio.test.ts: new describe block with two tests — a running deploy + no agent run doesn't say "Nothing yet" and opens exactly one tail; with nothing running, "Now" still says "Nothing yet." The first fails on unmodified code (verified).

bun test is green; the check's tsc --noEmit is clean. The check's other 6 failures (git push/auth in apps.test.ts, pulls.test.ts, cross-repo-pull.test.ts, apps-adversarial.test.ts, web.test.ts) are pre-existing sandbox/environment issues unrelated to this change — verified they fail identically on main before my edits.

Closes #163