feat(agent): event timeline API, SSE stream, Coolify DDL, env template

- Add agent_session_events table + GET/POST events + SSE stream routes
- Build Agent tab: hydrate from events + EventSource while running
- entrypoint: create agent_sessions + agent_session_events on container start
- .env.example for AGENT_RUNNER_URL, AGENT_RUNNER_SECRET, DATABASE_URL

Made-with: Cursor

.env.example

@@ -0,0 +1,23 @@
+# Copy to Coolify environment variables (or .env.local for dev). Do not commit secrets.
+
+# --- Postgres (Coolify internal service DNS, same stack as this app) ---
+# Example: postgresql://USER:PASS@<coolify-service-uuid>:5432/vibn
+DATABASE_URL=
+POSTGRES_URL=
+
+# --- Public URL of this Next app (OAuth callbacks, runner callbacks) ---
+NEXTAUTH_URL=https://vibnai.com
+NEXTAUTH_SECRET=
+
+# --- vibn-agent-runner (same Docker network: http://<service-name>:3333 — or public https://agents.vibnai.com) ---
+AGENT_RUNNER_URL=http://localhost:3333
+
+# --- Shared secret: must match runner. Required for PATCH session + POST /events ingest ---
+AGENT_RUNNER_SECRET=
+
+# --- Optional: one-shot DDL via POST /api/admin/migrate ---
+# ADMIN_MIGRATE_SECRET=
+
+# --- Google OAuth / Gemini (see .google.env locally) ---
+GOOGLE_CLIENT_ID=
+GOOGLE_CLIENT_SECRET=