Add GitHub Actions CI

Backend tests (uv), frontend lint, build and npm audit, and a Docker
build, on every push to main and every pull request.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: natrajexplore

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  backend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: backend
+    steps:
+      - uses: actions/checkout@v5
+      - uses: astral-sh/setup-uv@v6
+      - run: uv sync --frozen
+      - run: uv run pytest -q
+
+  frontend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: frontend
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-node@v5
+        with:
+          node-version: 24
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run build
+      - run: npm audit --omit=dev --audit-level=high
+
+  docker:
+    runs-on: ubuntu-latest
+    needs: [backend, frontend]
+    steps:
+      - uses: actions/checkout@v5
+      - run: docker build -t netverse:ci .