add workflow docs

PROJECT.md

@@ -1,7 +1,7 @@
 # UI Stock Tracker — Project Documentation
 
 **Status:** ✅ Complete and running
-**Last updated:** 2026-03-28
+**Last updated:** 2026-03-29
 
 ---
 
@@ -141,6 +141,24 @@ Stage 3 — runtime
 
 ---
 
+## CI/CD — Gitea Actions
+
+A workflow at `.gitea/workflows/docker-build.yml` automatically builds and pushes the Docker image on every push to `main`.
+
+**What it does:**
+1. Checks out the repo
+2. Logs in to the private container registry at `registry.alwisp.com` using `gitea.REGISTRY_USER` + `secrets.REGISTRY_TOKEN`
+3. Builds and pushes `registry.alwisp.com/{owner}/{repo}:latest`
+
+**Runner:** `catthehacker/ubuntu:act-latest` (self-hosted compatible)
+
+After a push triggers the build, pull the updated image on Unraid:
+```bash
+docker pull registry.alwisp.com/{owner}/{repo}:latest
+```
+
+---
+
 ## Build & Deploy
 
 ```bash
@@ -178,6 +196,9 @@ Original design used separate `frontend` and `backend` Docker services in docker
 
 ```
 ui-tracker/
+├── .gitea/
+│   └── workflows/
+│       └── docker-build.yml  # Build + push to registry.alwisp.com on push to main
 ├── Dockerfile              # 3-stage single-container build
 ├── docker-compose.yml      # Single service, port 8080, ./data volume
 ├── nginx.conf              # Serves frontend, proxies /api/ to Node