Add Refresh button to feed

[cosmo-coderbots]

Summary

• Adds a Refresh button between the composer and the post feed
• Clicking it fetches new posts from the server without a full page reload, preserving scroll position and client state
• Uses refresh() from next/cache via a Server Action — the correct Next.js 16 approach (client-side router.refresh() was being blocked by cross-origin dev resource protection when tunnelled through Cloudflare)
• Adds *.trycloudflare.com to allowedDevOrigins in next.config.ts so HMR and RSC requests aren't blocked in dev

Test plan

• Start dev server and open the app
• Post or insert a new record directly in the DB
• Click Refresh — new post should appear at the top without a page reload
• Confirm the button shows "Refreshing…" while in flight and re-enables after
• Confirm existing composer state (typed text, image preview) is preserved across a refresh

🤖 Generated with Claude Code

[cosmo-coderbots]

Automated visual review

Verdict: ✅ Verified

What I checked: Clicked the Refresh button after inserting a new post directly into the DB, with draft text already typed in the composer.

Observed:

• Refresh button is rendered between the composer and feed ✓
• New post ("Brand new post to test the refresh! 🎉") appeared at the top of the feed without a full page reload ✓
• Composer text ("Testing composer state preservation during refresh...") was fully preserved after refresh ✓
• Button re-enabled after the refresh completed ✓

Steps taken:

1. Opened app at http://localhost:3200, confirmed Refresh button visible
2. Typed draft text into the composer
3. Inserted a new post directly into Postgres via psql
4. Clicked Refresh — new post appeared at top; composer text intact

Before (initial load):

After (post-refresh):

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Reviewed from commit 8314c2921d7b22210880f8e7721717f9103e257a on branch pr-2. Screenshots hosted on claude-reviews/pr-2.