ci: proper Rust+Python CI workflow; cargo fmt + clippy clean

Replace the stale Django CI template with a CI workflow that builds and
tests both codebases: cargo fmt/clippy/build/test for the hh client and
pytest across Python 3.10-3.12 for the server. Apply cargo fmt and fix
all clippy lints so the gates pass.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: CI
+
+on:
+  push:
+    branches: [main, hack-house]
+  pull_request:
+    branches: [main]
+
+jobs:
+  rust:
+    name: rust client (hh)
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: hh
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: hh
+      - run: cargo fmt --all --check
+      - run: cargo clippy --all-targets -- -D warnings
+      - run: cargo build --verbose
+      - run: cargo test --verbose
+
+  python:
+    name: python server
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+          cache: pip
+      - run: pip install -r requirements.txt
+      - run: pytest -q