docs: finalize PodMan architecture and write full integration specs

Replaces v1 plan with locked architecture:
- Hermes orchestrator: POST /ingest → Gemini Vision → MongoDB → event detection → Gemini Live 2.5 voice via LiveKit Agents
- Four MongoDB collections: engineer_states, ownership_map, events, nudges
- Continual learning via ownership_map persisting across sessions

New files: docs/idea.md, docs/gemini.md, docs/livekit.md, docs/mongodb.md, docs/digitalocean.md, docs/demo-setup.md
Updated: README.md, docs/PLAN.md (12-hour build plan), database/README.md, infra/README.md, .env.example

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FFbfi4Cmb7BY75Wtne7bZn

.env.example

@@ -1,26 +1,24 @@
 # Copy to .env and fill in. Never commit .env.
 
-# --- LiveKit (realtime transport) ---
-LIVEKIT_URL=
+# --- LiveKit (realtime transport + voice delivery) ---
+LIVEKIT_URL=wss://your-project.livekit.cloud
 LIVEKIT_API_KEY=
 LIVEKIT_API_SECRET=
 
-# --- Gemini (vision + voice) ---
+# --- Gemini (vision + event detection + voice) ---
 GEMINI_API_KEY=
-GEMINI_VISION_MODEL=gemini-3.5-flash
-GEMINI_LIVE_MODEL=
+GEMINI_VISION_MODEL=gemini-2.0-flash
+GEMINI_LIVE_MODEL=gemini-live-2.5-flash
 
-# --- GitHub (state fusion + PR action) ---
-GITHUB_TOKEN=
-GITHUB_REPO=owner/name
-
-# --- MongoDB Atlas + Voyage (continual-learning memory) ---
-MONGODB_URI=
-VOYAGE_API_KEY=
+# --- MongoDB Atlas (engineer state, ownership map, events, nudges) ---
+MONGODB_URI=mongodb+srv://<user>:<pass>@cluster.mongodb.net/podman
 
 # --- Backend server ---
 PORT=8787
 
+# --- Nudge cooldown (ms) — set to 0 during demo if needed ---
+NUDGE_COOLDOWN_MS=180000
+
 # --- Frontend (Vite — must be VITE_ prefixed to reach the client) ---
-VITE_LIVEKIT_URL=
+VITE_LIVEKIT_URL=wss://your-project.livekit.cloud
 VITE_BACKEND_URL=http://localhost:8787