Add simple web UI for search

[MakiDevelop]

What needs to be done

Add a minimal web UI served by serve.py so users can search from a browser.

Which file(s) to modify

• serve.py — serve an HTML page at /

Proposed approach

1. Embed a single HTML page with a search box (inline CSS/JS, no build step)
2. On submit, call /search?q=... via fetch()
3. Display results as a list with signal_score, route, title, core_insight

The HTML should be embedded as a string constant in serve.py (no static file serving needed for v1).

Design goals

• Zero additional dependencies
• Works without JavaScript bundler
• Clean, minimal design (think: Hacker News simplicity)
• Shows scoring dimensions in a compact format

Acceptance criteria

• Visit http://localhost:8780/ shows a search page
• Search results display with scores and routes
• No external CSS/JS dependencies (everything inline)
• Mobile-friendly layout