feat(01-01): add test scaffold, health and static asset tests, fix deprecated APIs

- requirements-dev.txt with pytest and httpx
- tests/conftest.py: client and tmp_data_dir fixtures
- tests/test_health.py: GET /health returns 200 with {"status": "ok"}
- tests/test_static.py: no CDN URLs in templates, dashboard returns 200
- Fix imptune/api/pages.py: use request= kwarg in TemplateResponse (Starlette compat)
- Fix imptune/main.py: replace deprecated on_event with asynccontextmanager lifespan

imptune/api/pages.py

@@ -11,9 +11,9 @@ templates = Jinja2Templates(directory=str(Path(__file__).parent.parent / "templa
 @router.get("/", response_class=HTMLResponse)
 def dashboard(request: Request):
     return templates.TemplateResponse(
-        "dashboard.html",
-        {
-            "request": request,
+        request=request,
+        name="dashboard.html",
+        context={
             "recent_printers": [],
             "recent_packages": [],
         },

imptune/main.py

@@ -1,3 +1,5 @@
+import os
+from contextlib import asynccontextmanager
 from pathlib import Path
 
 from fastapi import FastAPI
@@ -6,7 +8,15 @@ from fastapi.staticfiles import StaticFiles
 from imptune.api import health, pages
 from imptune.config import DATA_DIR, DRIVERS_DIR
 
-app = FastAPI(title="ImpTune")
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    os.makedirs(DATA_DIR, exist_ok=True)
+    os.makedirs(DRIVERS_DIR, exist_ok=True)
+    yield
+
+
+app = FastAPI(title="ImpTune", lifespan=lifespan)
 
 # Serve baked-in static assets (pico.min.css, htmx.min.js, alpine.min.js)
 _static_dir = Path(__file__).parent / "static"
@@ -15,11 +25,3 @@ app.mount("/static", StaticFiles(directory=str(_static_dir)), name="static")
 # Register routers
 app.include_router(health.router)
 app.include_router(pages.router)
-
-
-@app.on_event("startup")
-def on_startup():
-    import os
-
-    os.makedirs(DATA_DIR, exist_ok=True)
-    os.makedirs(DRIVERS_DIR, exist_ok=True)