Docs: Add comprehensive README with local dev and production deployment guide

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -2,3 +2,141 @@
 _Organize your reaction images._
 
 ![Reactbin UI](.img/reactbin-ui.png)
+
+A self-hosted reaction image board. Single owner account, tag-based browsing, S3-compatible image storage.
+
+---
+
+## Local development
+
+```bash
+cp .env.example .env
+# Edit .env — defaults work out of the box for local dev
+docker compose up
+```
+
+- UI: http://localhost:4200
+- API: http://localhost:8000
+- MinIO console: http://localhost:9001 (minioadmin / minioadmin)
+
+The API serves on port 8000 directly in dev. In production the nginx ingress routes `/api/` there.
+
+### Running tests
+
+```bash
+make test-unit          # pytest unit tests (no Docker)
+make test-integration   # builds api-test image, runs full suite against Postgres + MinIO
+```
+
+### Production image builds
+
+```bash
+make build-prod         # builds reactbin-api-prod:latest from api/Dockerfile.prod
+make verify-prod        # smoke-tests the production image
+make build-ui-prod      # builds reactbin-ui-prod:latest from ui/Dockerfile.prod
+make verify-ui-prod     # smoke-tests the production UI image
+```
+
+---
+
+## Production deployment (k3s)
+
+### Cluster prerequisites
+
+- nginx ingress controller
+- cert-manager with a `letsencrypt-prod` ClusterIssuer
+- Vault Secrets Operator (VSO) installed and connected to Vault
+- Vault KV v2 secrets populated (see below)
+
+### Vault secrets
+
+Two KV v2 paths. VSO syncs these into Kubernetes Secrets automatically.
+
+**`reactbin/api/config`** → K8s Secret `api-env`
+
+| Key | Notes |
+|-----|-------|
+| `DATABASE_URL` | `postgresql+asyncpg://user:pass@host:5432/db` |
+| `JWT_SECRET_KEY` | Long random string — `openssl rand -base64 48` |
+| `OWNER_USERNAME` | Login username |
+| `OWNER_PASSWORD` | Login password |
+| `S3_ENDPOINT_URL` | `http://minio.reactbin.svc.cluster.local:9000` |
+| `S3_BUCKET_NAME` | `reactbin` |
+| `S3_ACCESS_KEY_ID` | Same value as `MINIO_ROOT_USER` |
+| `S3_SECRET_ACCESS_KEY` | Same value as `MINIO_ROOT_PASSWORD` |
+| `API_BASE_URL` | `https://<your-domain>` |
+| `LOGIN_TRUSTED_PROXY_IPS` | Pod CIDR of nginx ingress pods, e.g. `10.42.0.0/16` — needed for per-client login rate limiting behind the ingress |
+
+**`reactbin/minio/credentials`** → K8s Secret `minio-credentials`
+
+| Key | Notes |
+|-----|-------|
+| `MINIO_ROOT_USER` | MinIO admin username |
+| `MINIO_ROOT_PASSWORD` | `openssl rand -base64 32` |
+
+### Apply order
+
+```bash
+# 1. Namespace first
+kubectl apply -f k8s/namespace.yaml
+
+# 2. Vault CRDs — wait for VSO to create api-env and minio-credentials Secrets
+kubectl apply -f k8s/vault/
+kubectl get secret -n reactbin api-env minio-credentials   # wait until both appear
+
+# 3. API, UI, Ingress — replace 'latest' tags and <your-domain> first
+kubectl apply -f k8s/api/ -f k8s/ui/ -f k8s/ingress.yaml
+kubectl rollout status deployment/api -n reactbin          # Alembic init container runs here
+
+# 4. MinIO — wait for StatefulSet ready before running the bucket init Job
+kubectl apply -f k8s/minio/service.yaml -f k8s/minio/statefulset.yaml
+kubectl rollout status statefulset/minio -n reactbin
+kubectl apply -f k8s/minio/init-job.yaml
+```
+
+Before applying: substitute real image tags in the Deployment manifests and replace `<your-domain>` in `k8s/ingress.yaml`.
+
+### Updating a secret
+
+1. Update the value in Vault
+2. Force VSO to sync immediately (otherwise waits up to 1 hour):
+   ```bash
+   kubectl annotate vaultstaticsecret api-secret -n reactbin \
+     secrets.hashicorp.com/force-sync=$(date +%s) --overwrite
+   ```
+3. Restart the deployment to pick up the new Secret:
+   ```bash
+   kubectl rollout restart deployment/api -n reactbin
+   ```
+
+### Validating manifests
+
+```bash
+make validate-k8s   # yamllint + kubectl apply --dry-run=client (requires kubeconfig)
+```
+
+---
+
+## Environment variables reference
+
+All variables are read at startup from environment / `.env`.
+
+| Variable | Default | Notes |
+|----------|---------|-------|
+| `DATABASE_URL` | — | Async DSN: `postgresql+asyncpg://...` |
+| `JWT_SECRET_KEY` | — | Required; use a long random string in production |
+| `JWT_EXPIRY_SECONDS` | `86400` | Token lifetime (24 h) |
+| `OWNER_USERNAME` | — | Single owner account username |
+| `OWNER_PASSWORD` | — | Single owner account password |
+| `S3_ENDPOINT_URL` | — | MinIO or any S3-compatible endpoint |
+| `S3_BUCKET_NAME` | `reactbin` | |
+| `S3_ACCESS_KEY_ID` | — | |
+| `S3_SECRET_ACCESS_KEY` | — | |
+| `S3_REGION` | `us-east-1` | |
+| `MAX_UPLOAD_BYTES` | `52428800` | 50 MiB |
+| `API_BASE_URL` | — | Used for generating public URLs |
+| `API_DOCS_ENABLED` | `true` | Set to `false` in production |
+| `LOGIN_MAX_FAILURES` | `5` | Failed attempts before cooldown |
+| `LOGIN_WINDOW_SECONDS` | `300` | Sliding window for failure count |
+| `LOGIN_COOLDOWN_SECONDS` | `900` | Lock duration after threshold hit |
+| `LOGIN_TRUSTED_PROXY_IPS` | `""` | Comma-separated CIDRs of trusted upstream proxies |