docs: update deployment section with current production state

- Document production URL (comparaison.local.tophermayor.com)
- Detail host (ubuntu/192.168.50.61), Traefik ingress, shared Postgres
- Add Docker label routing, proxy-net network info
- List recent fixes: userId in comparison inserts, OpenAI getClient(), BETTER_AUTH_SECRET

README.md

@@ -85,6 +85,44 @@ npm run dev
 docker compose up -d
 ```
 
+## Deployment
+
+**Production URL:** [https://comparaison.local.tophermayor.com](https://comparaison.local.tophermayor.com)
+
+| Detail | Value |
+|---|---|
+| Host | `ubuntu` (`192.168.50.61`) |
+| Compose file | `/srv/compose/comparaison/docker-compose.yml` |
+| Reverse proxy | Traefik (shared instance on `proxy-net`) |
+| Database | Shared PostgreSQL (`postgres-shared` container on `proxy-net`) |
+| Routing | Docker labels on the app container (Traefik router/rules) |
+
+### Production Setup
+
+1. **Traefik Ingress** — A shared Traefik instance handles TLS termination and routes traffic to the app container via Docker labels. The app joins the `proxy-net` network so Traefik can reach it.
+
+2. **Shared PostgreSQL** — A standalone `postgres-shared` container provides the database. The comparaison app connects to it over `proxy-net`. No separate DB container is defined in the app's compose file.
+
+3. **Environment** — The following are configured in the production environment:
+   - `DATABASE_URL` — Points to the shared Postgres instance
+   - `BETTER_AUTH_SECRET` — Random secret for session signing
+   - `OPENAI_API_KEY`, `TAVILY_API_KEY`, `PERPLEXITY_API_KEY` — LLM provider keys
+   - `NEXT_PUBLIC_APP_URL` — `https://comparaison.local.tophermayor.com`
+
+### Deploying Updates
+
+```bash
+# On ubuntu (192.168.50.61)
+cd /srv/compose/comparaison
+docker compose pull && docker compose up -d
+```
+
+### Recent Fixes
+
+- Added `userId` to comparison inserts so saved comparisons are properly associated with authenticated users
+- Fixed OpenAI provider `getClient()` to correctly initialize the OpenAI client
+- Added `BETTER_AUTH_SECRET` to production environment for proper session management
+
 ## Project Structure
 
 ```