feat(HAI-077): add CI/CD workflows for PRs, releases, and manual testing

- Add CI workflow for pull requests and pushes with lint, test, and build steps
- Add release workflow for tagged versions with automated publishing
- Add manual test-release workflow for on-demand validation
- Add workflow validation tests and remove obsolete build/test files
- Update README with CI/CD documentation and badge references

.github/workflows/ci.yml

@@ -0,0 +1,43 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  ci:
+    name: Build & Test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: pnpm
+
+      - name: Install Bun
+        uses: oven-sh/setup-bun@v2
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Build
+        run: pnpm build
+
+      - name: Test
+        run: pnpm test
+
+      - name: Build standalone binary
+        run: pnpm build:exe
+
+      - name: Verify binary exists
+        run: test -f packages/cli/dist/hai