Update UI to read from the database instead of mock data

[Pabl0cks]

Wire the UI to the real database so it stops relying on mock data.

Pasting here some of the pending subissues from #22:

• UI: display multiple voting stages per proposal (likely ordered by date desc), showing the latest by default with an expand/collapse to reveal older ones.
• Decide how to handle snapshot votes that aren’t tied to proposals. For now they remain unlinked (we should probably not show in the UI, but worth aligning with Patrick)
• Improve matching input by using snapshot author name instead of just address, to give the LLM more context (tracked here: Snapshot import #12).
• Edge case: a single tally vote that merges multiple forum proposals. Currently results in null proposal_id. Decide whether tally/snapshot items should support linking to multiple proposals. Example: "[CONSTITUTIONAL] Remove Cost Cap, Update Executors, Disable Legacy USDT Bridge",