fix: proxy WebSocket upgrades to the API in dev (#692)

The Vite dev proxy forwards `/v1` as plain HTTP with no `ws: true`, so the
WebSocket upgrade for `/v1/agents/events` is never proxied. The socket does not
open, does not error, and does not close — it just sits silent — so every live
agent view is empty under `npm run dev` while working in a production build,
where the frontend is served from the same origin as the API.

That covers the per-agent live trace on the Agents page, which subscribes via
`useAgentEvents` (`frontend/src/lib/useAgentEvents.ts`).

The silence is what makes it costly: with no error to see, it reads as "no
events are being emitted" rather than "the transport never connected", so the
search starts on the server side.

Verified on Windows 11 with `jarvis start` running: before, a
`new WebSocket('ws://localhost:5173/v1/agents/events')` from the dev page never
fired open, error or close within 6s. After, it opens, and a real agent tick
delivers 8 events (agent_tick_start, inference_start/end, tool_call_start/end,
agent_tick_end).

`changeOrigin` is set alongside so the upgrade request carries the target's
host, which some setups require when the API is not on localhost.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

frontend/vite.config.ts

@@ -54,7 +54,15 @@ export default defineConfig({
   server: {
     port: 5173,
     proxy: {
-      '/v1': process.env.VITE_API_URL || 'http://localhost:8000',
+      // ws: true is required for the /v1/agents/events WebSocket. Without it
+      // Vite proxies the HTTP request but not the upgrade, so the socket never
+      // opens — no error, no close event, just silence — and every live agent
+      // view sits empty in dev while working in a production build.
+      '/v1': {
+        target: process.env.VITE_API_URL || 'http://localhost:8000',
+        changeOrigin: true,
+        ws: true,
+      },
       '/health': process.env.VITE_API_URL || 'http://localhost:8000',
       '/api': process.env.VITE_API_URL || 'http://localhost:8000',
     },