ci: add GitHub Actions workflow (ubuntu/macos/windows × Python 3.9–3.12)

Zero-dependency stdlib project — no pip install step for tests.
Ruff lint step added after fixing SIM105 ignore, UP009 headers,
unused import (F401) and unused variable (F841).

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

Author: Lukas Geiger

.github/workflows/ci.yml

@@ -0,0 +1,31 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test:
+    name: Python ${{ matrix.python-version }} / ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Run tests (stdlib only, zero deps)
+        run: python -m unittest discover -s tests -v
+
+      - name: Lint (ruff)
+        run: |
+          pip install ruff
+          python -m ruff check .

fable_hunter.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 """
 fable-5-hunter
 ==============

pyproject.toml

@@ -54,7 +54,7 @@ target-version = "py39"
 
 [tool.ruff.lint]
 select = ["E", "W", "F", "I", "B", "C4", "UP", "SIM"]
-ignore = ["E501"]
+ignore = ["E501", "SIM105"]
 
 [tool.ruff.format]
 quote-style = "double"

tests/test_hunter.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 """
 Tests for fable-5-hunter (standard library only, zero-dependency).
 
@@ -655,7 +654,6 @@ def test_deep_merge_in_load_config(self):
         self.assertEqual(cfg["model_id"], "claude-fable-5")  # default preserved
 
     def test_default_notifiers_are_desktop_and_file(self):
-        cfg = fh.load_config()
         # When no config file is present the defaults apply.
         # We just test the DEFAULT_CONFIG directly since load_config merges from it.
         self.assertIn("desktop", fh.DEFAULT_CONFIG["notifiers"])
@@ -714,7 +712,6 @@ def test_acquire_blocks_second_instance(self):
             self.assertFalse(result)
 
     def test_acquire_takes_over_stale_lock(self):
-        import time as _time
         with tempfile.TemporaryDirectory() as tmp:
             lock = Path(tmp) / "hunter.lock"
             lock.write_text("12345", encoding="utf-8")