chore(uniweb): make pnpm dev usable after the same-origin switch

Same-origin (Caddy) means the SPA reaches /api and /nats through its own
origin in production, but those relative paths do not exist on the bare Vite
dev server, so `pnpm dev` no longer connects. busService already reads
VITE_BUS_HTTP / VITE_BUS_WS as overrides of the same-origin defaults — this
documents that path (Option A, no proxy code) and moves the dev server off the
port reserved by an unrelated local app.

- vite.config: dev server port 5173 -> 5174 (5173 is in use by another local
  app). strictPort left off so Vite falls back to the next free port. Comment
  explains the same-origin/dev split and the env-var override.
- app.md: Ejemplo and the CORS gotcha document the exact dev command
  (VITE_BUS_HTTP/WS pointing at a cluster node) on :5174 and the same-origin
  production model.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/vite.config.ts

@@ -3,12 +3,16 @@ import react from "@vitejs/plugin-react";
 
 export default defineConfig({
   plugins: [react()],
-  // The SPA talks DIRECTLY to the bus (signed HTTPS control plane + nats.ws data
-  // plane), so there is no gateway and no /api proxy. The dev server runs on 5173 to
-  // match the bus CORS allowlist (--cors-origins http://localhost:5173). Point the
-  // SPA at a cluster node with VITE_BUS_HTTP / VITE_BUS_WS (see busService.ts).
+  // In production the SPA is served same-origin behind Caddy, which proxies /api and
+  // /nats to the cluster; those relative paths do not exist on the bare dev server, so
+  // `pnpm dev` must be pointed at a real cluster node with VITE_BUS_HTTP / VITE_BUS_WS
+  // (busService.ts uses them as overrides of the same-origin defaults). Example:
+  //   VITE_BUS_HTTP=https://<node>:8470 VITE_BUS_WS=wss://<node>:8480 pnpm dev
+  // The dev server runs on 5174 (5173 is reserved for an unrelated local app). Add the
+  // dev origin (http://localhost:5174) to the node's --cors-origins allowlist. strictPort
+  // is left off, so Vite falls back to the next free port if 5174 is busy.
   server: {
     host: true,
-    port: 5173,
+    port: 5174,
   },
 });