fix(docker): start the dev server and pick up source changes

Two separate reasons the containerised dev workflow did not work:

- CMD ran `npm run dev -- --host`. With no TTY under `docker compose up
  -d`, npm printed its banner and exited 0 immediately, so the dev server
  never started. Invoking vite directly keeps it running.
- Vite's watcher receives no file-change events through a Docker Desktop
  bind mount, so it served stale modules indefinitely: edits appeared to
  have no effect and HMR never fired. Polling is opt-in via
  VITE_USE_POLLING, set by the compose file, so native dev is unaffected.

Dockerfile

@@ -5,7 +5,10 @@ COPY package*.json ./
 RUN npm ci
 COPY . .
 EXPOSE 5173
-CMD ["npm", "run", "dev", "--", "--host"]
+# Invoke vite directly rather than through `npm run`: under `docker compose
+# up -d` (no TTY, no stdin) the npm wrapper printed its banner and exited 0
+# immediately, so the dev server never came up.
+CMD ["node", "node_modules/vite/bin/vite.js", "--host"]
 
 # --- Build stage ---
 # No VITE_API_URL build arg: the production image uses runtime config (/config.js)

vite.config.ts

@@ -11,6 +11,12 @@ export default defineConfig({
     },
   },
   server: {
+    // Bind-mounted source on Docker Desktop (Windows/macOS) does not deliver
+    // inotify events, so Vite never sees host edits and silently serves stale
+    // modules. Polling is opt-in via the compose file so native dev is unaffected.
+    watch: process.env.VITE_USE_POLLING
+      ? { usePolling: true, interval: 300 }
+      : undefined,
     proxy: {
       '/api': {
         target: 'http://localhost:3000',