📝 Improve docs after split

CONTRIBUTING.md

@@ -12,7 +12,7 @@ the rules so agents and humans don't diverge.
 1. Clone the repository.
 2. Install Node.js >= 26 — see [.node-version](./.node-version); the exact pinned
    version is what CI and the runner image use.
-3. `npm install`.
+3. `npm ci`.
 4. `npm run setup` — the one-time clone configuration (currently registers the
    commit-message template).
 
@@ -20,7 +20,7 @@ the rules so agents and humans don't diverge.
 
 - **Build:** `npm run build`
 - **Test:** `npm run test`, `npm run test:ci`
-- **Watch:** `npm run watch`
+- **Watch:** `npm run watch` - re-runs tests on file save, humans only
 - **Checks:** `npm run check`, `npm run fix`
 - **Verify:** `npm run verify` — the definition of done
 - **Maintenance:** `npm run maintain` — advisory only