Build local product stack with Vault-managed secrets (#42)

README.md

@@ -32,6 +32,23 @@ Each application owns its dependencies and build configuration. Shared Dart and
 Flutter packages can be reused by a future mobile app; mobile runners are not
 currently included. Local `.vscode/` configuration is ignored.
 
+## Local Docker development
+
+```sh
+make build && make up
+```
+
+This builds the product images and starts an isolated Vault, authenticated MongoDB
+replica set and NATS JetStream. First startup intentionally stops after bootstrap
+until you set the Resend API key and verified sender in Vault's `kv/email` secret.
+Then rerun `make up` to start notifications, BFF and the frontend at
+[https://localhost:5126](https://localhost:5126).
+
+All image inputs resolve to current stable releases and are pinned by digest for
+the build. Services fetch secrets from Vault; Mongo application credentials come
+from Vault's database plugin. See the [local development guide](docs/local-development.md)
+for Vault provisioning, local HTTPS trust, lifecycle commands and verification.
+
 ## Run the consumer app
 
 Requires Flutter **3.47.0 or later** with Dart **3.13.0 or later** (below Dart 4), matching