fix: address final review findings for service clients plan

Fixes 9 numbered findings + 7 minor fixes from the whole-plan review of
the MyWhoosh/Garmin service clients (Plan 3):

Garmin uploader (app/garmin/uploader.py):
- Detect Garmin-rejected imports (failures without successes) and raise
  new GarminImportRejected instead of reporting them as successful.
- Reclassify 429/rate-limit/500 login failures as transient instead of
  falling through to permanent auth errors; unrecognized login failures
  are now treated as transient (retryable) rather than GarminAuthError.
- Mirror the auth-token check from the login branch into the import
  branch so 401-at-import-time raises GarminAuthError instead of
  propagating raw.
- Add common GarminError base class, hoist transient-token tuple to a
  shared module constant, check response.status_code==409 before the
  duplicate substring fallback, and create the tokenstore dir 0o700.

MyWhoosh client (app/mywhoosh/client.py):
- Add optional max_pages bound to list_activities pagination.
- Add aclose()/__aenter__/__aexit__ so the client's own httpx.AsyncClient
  gets closed, while never closing an injected client.
- Guard the two remaining unguarded JSON-decode paths (login body,
  download-fit metadata) so malformed bodies raise
  MyWhooshIntegrationError instead of raw ValueError/AttributeError.
- Row-level malformation (missing id/activityFileId, unparseable
  startDatetime) is now skipped rather than aborting the whole page;
  envelope-shape failures still raise. id/activityFileId checks use
  explicit None/"" comparisons instead of Python falsiness.
- Replace asserts in _authenticated_post with explicit exceptions;
  restrict the reauth retry to 401 only, treat 403 as immediately
  terminal; naive startDatetime values are now treated as already-UTC
  instead of host-local.

MyWhoosh tokenstore (app/mywhoosh/tokenstore.py):
- load() now treats any corrupt/malformed token file (bad JSON, missing
  keys, OS errors) as "absent" instead of raising, so a bad cache no
  longer permanently wedges a user.

pyproject.toml:
- Tighten garminconnect pin to >=0.3.10,<1 (import_activity requires
  0.3.10+).

Adds/updates tests across tests/mywhoosh/ and tests/garmin/ covering
all of the above, including a fake client that wraps GarminUploadBlocked
in a plain RuntimeError to mirror the real garminconnect library's MFA
error wrapping.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/mywhoosh/test_client_auth.py

@@ -1,7 +1,12 @@
 import httpx
 import pytest
 
-from app.mywhoosh.client import MyWhooshClient, MyWhooshAuthError
+from app.mywhoosh.client import (
+    MyWhooshAuthError,
+    MyWhooshClient,
+    MyWhooshIntegrationError,
+    MyWhooshTransientError,
+)
 from app.mywhoosh.models import MyWhooshToken
 from app.mywhoosh.tokenstore import MyWhooshTokenStore
 
@@ -37,3 +42,93 @@ async def test_invalid_credentials_raise_auth_error(tmp_path) -> None:
     )
     with pytest.raises(MyWhooshAuthError):
         await client.login("rider@example.com", "bad")
+
+
+@pytest.mark.asyncio
+async def test_login_returns_json_array_raises_integration_error(tmp_path) -> None:
+    async def handler(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(200, json=["not", "an", "object"])
+
+    client = MyWhooshClient(
+        MyWhooshTokenStore(tmp_path / "mywhoosh.json"),
+        http_client=httpx.AsyncClient(transport=httpx.MockTransport(handler)),
+    )
+    with pytest.raises(MyWhooshIntegrationError):
+        await client.login("rider@example.com", "bad")
+
+
+@pytest.mark.asyncio
+async def test_login_5xx_raises_transient_error(tmp_path) -> None:
+    async def handler(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(503, text="Service Unavailable")
+
+    client = MyWhooshClient(
+        MyWhooshTokenStore(tmp_path / "mywhoosh.json"),
+        http_client=httpx.AsyncClient(transport=httpx.MockTransport(handler)),
+    )
+    with pytest.raises(MyWhooshTransientError):
+        await client.login("rider@example.com", "secret")
+
+
+@pytest.mark.asyncio
+async def test_second_401_after_reauth_raises_auth_error(tmp_path) -> None:
+    login_call_count = 0
+
+    async def handler(request: httpx.Request) -> httpx.Response:
+        nonlocal login_call_count
+        if request.url.path.endswith("/activities"):
+            return httpx.Response(401, json={"message": "expired"})
+        if request.url.path.endswith("/login"):
+            login_call_count += 1
+            return httpx.Response(
+                200,
+                json={
+                    "Success": True,
+                    "AccessToken": "fresh-access",
+                    "RefreshToken": "fresh-refresh",
+                    "WhooshId": "w-1",
+                },
+            )
+        raise AssertionError(request.url)
+
+    store = MyWhooshTokenStore(tmp_path / "mywhoosh.json")
+    store.save(MyWhooshToken(access_token="stale", refresh_token=None, whoosh_id=None))
+    client = MyWhooshClient(store, http_client=httpx.AsyncClient(transport=httpx.MockTransport(handler)))
+
+    with pytest.raises(MyWhooshAuthError):
+        await client.list_activities("rider@example.com", "secret")
+
+    assert login_call_count == 1
+
+
+@pytest.mark.asyncio
+async def test_aclose_closes_self_owned_http_client(tmp_path) -> None:
+    store = MyWhooshTokenStore(tmp_path / "mywhoosh.json")
+    client = MyWhooshClient(store)
+
+    await client.aclose()
+
+    assert client.http.is_closed is True
+
+
+@pytest.mark.asyncio
+async def test_aclose_does_not_close_injected_http_client(tmp_path) -> None:
+    store = MyWhooshTokenStore(tmp_path / "mywhoosh.json")
+    injected = httpx.AsyncClient()
+    client = MyWhooshClient(store, http_client=injected)
+
+    await client.aclose()
+
+    assert injected.is_closed is False
+    await injected.aclose()
+
+
+@pytest.mark.asyncio
+async def test_client_usable_as_async_context_manager(tmp_path) -> None:
+    store = MyWhooshTokenStore(tmp_path / "mywhoosh.json")
+
+    async with MyWhooshClient(store) as client:
+        http_client = client.http
+        assert http_client.is_closed is False
+
+    assert http_client.is_closed is True