fix: GET/POST /api/athlete work without a pre-existing athlete.json

bincio/serve/server.py

@@ -449,8 +449,8 @@ async def get_athlete(bincio_session: Optional[str] = Cookie(default=None)) -> J
     user = _require_user(bincio_session)
     dd = _get_data_dir() / user.handle
     athlete_path = dd / "athlete.json"
-    if not athlete_path.exists():
-        raise HTTPException(404, "athlete.json not found — run bincio extract first")
+    data: dict = {}
+    if athlete_path.exists():
         data = json.loads(athlete_path.read_text(encoding="utf-8"))
     # Layer edits/athlete.yaml on top
     edits_path = dd / "edits" / "athlete.yaml"
@@ -480,8 +480,14 @@ async def save_athlete(
 ) -> JSONResponse:
     user = _require_user(bincio_session)
     dd = _get_data_dir() / user.handle
-    if not (dd / "athlete.json").exists():
-        raise HTTPException(404, "athlete.json not found — run bincio extract first")
+    athlete_path = dd / "athlete.json"
+    if not athlete_path.exists():
+        from datetime import datetime, timezone
+        athlete_path.write_text(json.dumps({
+            "bas_version": "1.0",
+            "generated_at": datetime.now(timezone.utc).isoformat(),
+            "power_curve": {},
+        }), encoding="utf-8")
     payload = await request.json()
     edits_dir = dd / "edits"
     edits_dir.mkdir(exist_ok=True)