Add README with build and deploy instructions

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

README.md

@@ -0,0 +1,33 @@
+# bbq
+
+Potluck signup app. No accounts — share a link, people claim slots.
+
+## Run locally
+
+```
+go build -o bbq . && ./bbq
+```
+
+Listens on `:8080`. Set `PORT` and `BBQ_DB` env vars to override.
+
+## Docker
+
+```
+docker compose up -d --build
+```
+
+Runs on `127.0.0.1:8090`. Data persists in a `bbq-data` volume.
+
+## Reverse proxy (Caddy)
+
+```
+bbq.example.com {
+    reverse_proxy localhost:8090
+}
+```
+
+## Regenerate DB layer
+
+```
+$(go env GOPATH)/bin/sqlc generate
+```