Add CI workflow for automated testing and linting

.github/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: CI
+
+permissions:
+    contents: read
+
+on:
+    pull_request:
+        types: [opened, synchronize]
+    workflow_dispatch:
+
+jobs:
+    test:
+        runs-on: ubuntu-latest
+
+        steps:
+            - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+
+            - uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6
+              with:
+                  node-version: "24.x"
+
+            - uses: oven-sh/setup-bun@3d267786b128fe76c2f16a390aa2448b815359f3 # v2
+
+            - name: Install dependencies
+              run: bun install
+
+            - name: Check (lint + format)
+              run: bun run check
+
+            - name: Type check
+              run: bun run typecheck
+
+            - name: Run tests
+              run: bun run test:run