Feature: start team run via API and stream live task state to dashboard

[ibrahimkzmv]

What

Adds an end-to-end path from OMA Core to the Forge UI: start a demo team run via the API, keep an in-memory run snapshot on the server, broadcast run_snapshot events over SSE, and drive the existing team-run dashboard from live state instead of static demo data.

Server

• POST /api/runs — start oma.runTeam on the registered forge-demo team (202; 409 if a run is already in progress)
• GET /api/runs/current — current run snapshot (status, goal, tasks)
• CurrentRun state updated from onPlanReady, onProgress, and final TeamRunResult
• run_snapshot events on the existing /api/events SSE stream

Web

• useForgeRun — loads current snapshot and health, subscribes to SSE, exposes Run demo
• Dashboard renders when tasks exist; empty state prompts before the first run

Why

v0.1 needs running workflows and real-time visualization. The dashboard UI was already in place with static demo data; this wires it to OMA Core through the existing health/SSE scaffold so Forge can show a live DAG during execution.

Out of scope for this PR: workflow file loading, trace/onTrace inspection, run history, and cancellation.

Checklist

• npm run lint passes
• npm test passes
• Added/updated tests for changed behavior
• No new runtime dependencies (or justified in the PR description)