chore(09-02): add Playwright dev deps and e2e package scaffolding

- Add pytest-playwright and playwright to requirements-dev.txt
- Create tests/e2e/__init__.py package marker
- Create tests/e2e/conftest.py with session-scoped live_server fixture

requirements-dev.txt

@@ -1,2 +1,4 @@
 pytest>=8.0
 httpx>=0.27
+pytest-playwright
+playwright

tests/e2e/conftest.py

@@ -0,0 +1,70 @@
+"""E2E test fixtures: live uvicorn server for Playwright."""
+from __future__ import annotations
+
+import os
+import socket
+import threading
+import time
+
+import httpx
+import pytest
+import uvicorn
+
+
+def _free_port() -> int:
+    with socket.socket() as s:
+        s.bind(("127.0.0.1", 0))
+        return s.getsockname()[1]
+
+
+@pytest.fixture(scope="session")
+def live_server(tmp_path_factory):
+    """Start the FastAPI app on a random port in a background thread."""
+    # Isolated data dir for E2E session
+    data_dir = tmp_path_factory.mktemp("imptune_e2e_data")
+
+    # Patch config module so the app uses the temp dir
+    import imptune.config as cfg
+
+    cfg.DATA_DIR = str(data_dir)
+    cfg.DB_PATH = str(data_dir / "imptune.db")
+    cfg.DRIVERS_DIR = str(data_dir / "drivers")
+    cfg.ICONS_DIR = str(data_dir / "icons")
+
+    os.makedirs(cfg.DRIVERS_DIR, exist_ok=True)
+    os.makedirs(cfg.ICONS_DIR, exist_ok=True)
+
+    # Also set env var so lifespan handler picks up correct dirs
+    os.environ["DATA_DIR"] = str(data_dir)
+
+    # Initialize DB against the tmp dir
+    from imptune.db.database import init_db
+
+    init_db()
+
+    from imptune.main import app
+
+    port = _free_port()
+    config = uvicorn.Config(app, host="127.0.0.1", port=port, log_level="error")
+    server = uvicorn.Server(config)
+    thread = threading.Thread(target=server.run, daemon=True)
+    thread.start()
+
+    base_url = f"http://127.0.0.1:{port}"
+    # Readiness poll via /health (up to 5 s)
+    deadline = time.time() + 5.0
+    while time.time() < deadline:
+        try:
+            r = httpx.get(f"{base_url}/health", timeout=0.5)
+            if r.status_code == 200:
+                break
+        except Exception:
+            pass
+        time.sleep(0.1)
+    else:
+        raise RuntimeError("live_server did not become ready within 5 s")
+
+    yield base_url
+
+    server.should_exit = True
+    thread.join(timeout=2.0)