ci: run typecheck + Vitest on every push to main/feat/** and on every PR

Until now the test suite was authoritative only when run locally;
nothing stopped a commit landing with `yarn test` red. Wire up a
GitHub Actions workflow that gates push + pull_request on both
`yarn typecheck` and `yarn test --run`.

The setup mirrors CLAUDE.md's "Setup walkthrough":
- Check the client into `<workspace>/Nitro-V3`.
- Check `duckietm/Nitro_Render_V3` as a sibling at
  `<workspace>/Nitro_Render_V3`, since the build / typecheck wire
  the renderer in via filesystem aliases that expect that layout.
- Symlink `Nitro-V3/node_modules/@nitrots/nitro-renderer` →
  `../../../Nitro_Render_V3` so `tsconfig.json`'s `include`
  entry pointing at `node_modules/@nitrots/nitro-renderer/src/**/*.ts`
  actually resolves.
- `yarn install --frozen-lockfile` in both repos, then run
  `yarn typecheck` and `yarn test --run` in the client.

Node 22 (matches the local toolchain). Yarn classic, with the
workflow's `setup-node` caching the `yarn.lock` of both repos so
subsequent runs don't reinstall from scratch.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -0,0 +1,62 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+      - 'feat/**'
+  pull_request:
+
+jobs:
+  check:
+    name: Type check + tests
+    runs-on: ubuntu-latest
+    steps:
+      # The build/dev/typecheck setup expects the Nitro renderer SDK to
+      # live as a sibling of this repo (see CLAUDE.md → Setup walkthrough).
+      # Mirror that here by checking the client into <workspace>/Nitro-V3
+      # and the renderer into <workspace>/Nitro_Render_V3.
+      - name: Checkout Nitro-V3
+        uses: actions/checkout@v4
+        with:
+          path: Nitro-V3
+
+      - name: Checkout Nitro_Render_V3 (sibling)
+        uses: actions/checkout@v4
+        with:
+          repository: duckietm/Nitro_Render_V3
+          path: Nitro_Render_V3
+
+      - name: Setup Node 22
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: yarn
+          cache-dependency-path: |
+            Nitro-V3/yarn.lock
+            Nitro_Render_V3/yarn.lock
+
+      # The renderer SDK is consumed via a filesystem symlink in
+      # node_modules/@nitrots/nitro-renderer; create it explicitly so
+      # tsgo (TS 7 native preview) can resolve the tsconfig `include`
+      # entry pointing at the renderer's `src/**/*.ts`.
+      - name: Symlink renderer into client node_modules
+        run: |
+          mkdir -p Nitro-V3/node_modules/@nitrots
+          ln -sfn ../../../Nitro_Render_V3 Nitro-V3/node_modules/@nitrots/nitro-renderer
+
+      - name: Install renderer SDK deps
+        working-directory: Nitro_Render_V3
+        run: yarn install --frozen-lockfile
+
+      - name: Install client deps
+        working-directory: Nitro-V3
+        run: yarn install --frozen-lockfile
+
+      - name: Type check (tsgo)
+        working-directory: Nitro-V3
+        run: yarn typecheck
+
+      - name: Vitest
+        working-directory: Nitro-V3
+        run: yarn test --run

CLAUDE.md

@@ -299,7 +299,10 @@ Fix shapes documented; both are reasonable PRs on their own.
 - **Skip-motivated god-hook splits are fine** — when a hook's actions
   mutate internal state, document the reason in the commit message and
   move on rather than forcing a bad split.
-- **`yarn test` must stay green** on every commit. Currently 113/113.
+- **`yarn test` must stay green** on every commit. Currently 163/163.
+  The GitHub Actions workflow at `.github/workflows/ci.yml` runs
+  `yarn typecheck` + `yarn test --run` on every push to `main` /
+  `feat/**` and on every PR — both must pass.
 - **Lint baseline**: don't regress. Some pre-existing errors (`FC<{}>`,
   `IMessageEvent | undefined` redundant union in the local sandbox where
   the renderer SDK isn't installed) are out of scope here.