docs: add testing + release checklist; fix contributing links

docs/testing/README.md

@@ -1,3 +1,82 @@
-# Testing guide
+# Testing
 
-Placeholder: see root `README.md` and `CONTRIBUTING.md` for current commands.
+This guide describes how to run Mission Control tests locally.
+
+## Quick start (repo root)
+
+```bash
+make setup
+make check
+```
+
+`make check` is the closest thing to “CI parity”:
+
+- backend: lint + typecheck + unit tests (with scoped coverage gate)
+- frontend: lint + typecheck + unit tests (Vitest) + production build
+
+## Backend tests
+
+From repo root:
+
+```bash
+make backend-test
+make backend-coverage
+```
+
+Or from `backend/`:
+
+```bash
+cd backend
+uv run pytest
+```
+
+Notes:
+
+- Some tests may require a running Postgres (see root `compose.yml`).
+- `make backend-coverage` enforces a strict coverage gate on a scoped set of modules.
+
+## Frontend tests
+
+From repo root:
+
+```bash
+make frontend-test
+```
+
+Or from `frontend/`:
+
+```bash
+cd frontend
+npm run test
+npm run test:watch
+```
+
+## End-to-end (Cypress)
+
+The frontend has Cypress configured in `frontend/cypress/`.
+
+Typical flow:
+
+1) Start the stack (or start backend + frontend separately)
+2) Run Cypress
+
+Example (two terminals):
+
+```bash
+# terminal 1
+cp .env.example .env
+docker compose -f compose.yml --env-file .env up -d --build
+```
+
+```bash
+# terminal 2
+cd frontend
+npm run e2e
+```
+
+Or run interactively:
+
+```bash
+cd frontend
+npm run e2e:open
+```