Adds ``g.typed`` — a lazy namespace accessor that wraps a curated set of
high-value read endpoints with Pydantic response models, while leaving the
132 existing methods entirely unchanged.

Design follows Option D from the issue discussion:

    g = Garmin(email, password)
    raw = g.get_stats(date)           # dict[str, Any] — unchanged
    stats = g.typed.get_stats(date)   # DailyStats (Pydantic model)

Scope of the first cut (7 methods, 6 response models):

    - get_stats / get_user_summary -> DailyStats
    - get_sleep_data               -> SleepData (with nested DailySleepDTO)
    - get_hrv_data                 -> HrvData | None
    - get_body_battery             -> list[BodyBatteryEntry]
    - get_training_readiness       -> list[TrainingReadiness]
    - get_activities_by_date       -> list[Activity]

Design notes:

- Lazy import. ``g.typed`` is a ``@functools.cached_property`` that imports
  ``garminconnect.typed`` on first access, so pydantic stays optional. If
  pydantic is missing, the import raises a clear install hint.
- Kept in a new ``[typed]`` extra (pydantic>=2.0.0) rather than promoted to
  a core dep, so the default ``pip install garminconnect`` footprint doesn't
  change.
- ``extra='allow'`` + all fields ``Optional`` — models tolerate Garmin schema
  drift (new firmware / subscription tiers add fields) and partial responses
  (privacy-protected accounts, missing device data). Unknown fields land in
  ``model_extra`` for callers who want them.
- Validation failures raise ``GarminConnectResponseValidationError`` with the
  unvalidated response preserved on ``.raw`` so users can fall back without
  losing data.
- ``get_training_readiness`` wrapper reflects the real list-shaped response
  (the existing ``dict[str, Any]`` annotation on the raw method is wrong but
  out of scope here).

Marked **experimental** in module and class docstrings — model shapes may
change between minor releases while the pattern stabilises.

Tests (16 mocked, all green):

- accessor returns cached ``TypedGarmin``
- each wrapper calls through to the raw method and validates the response
- extra fields tolerated (preserved in ``model_extra``)
- missing fields default to ``None``
- validation errors raise ``GarminConnectResponseValidationError`` with
  ``.raw`` populated
- list endpoints with non-list responses return ``[]``
- ``get_hrv_data`` ``None`` passes through unchanged

Lint clean under ruff + mypy + black + isort.

`is_cn=True` correctly routes the SSO and Connect API endpoints via the
domain-aware `_sso` / `_connect` / `_connectapi` attributes, but the DI
OAuth2 token endpoint stayed hardcoded to `diauth.garmin.com`. CN users
don't exist in the .com user database, so:

- Token exchange (post-SSO) succeeded for fresh logins because the SSO
  ticket validates server-side regardless of which DI auth host receives
  it (the .com endpoint accepts the ticket and issues a token whose JWT
  payload still carries `iss=https://diauth.garmin.cn` — confusing!)
- BUT token refresh fails with 400:
  `{"error":"invalid_grant","error_description":"User doesn't exist in
  DB for GarminGUID: <uuid>"}`
  because the refresh path looks up the user by GUID in the host's DB.

This matters in practice: the access token's TTL is ~4 hours, so any CN
account that stays logged in longer than a single session will hit the
refresh path and break.

Fix: store `_di_token_url` as an instance attribute built from `domain`
(same pattern as `_sso` / `_connect`), and use it in `_exchange_ticket()`
and `_refresh_di_token()`. The module-level `DI_TOKEN_URL` constant is
kept for backwards compatibility with external imports.

Reproduce: `Garmin(email, password, is_cn=True).login()` then wait
4+ hours, then make any API call → 401 → 400 invalid_grant on refresh.

After fix: token refresh hits `https://diauth.garmin.cn/...` → 200.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

fix: route DI token endpoint to garmin.cn for CN accounts

Co-authored-by: Copilot Autofix powered by AI <[email protected]>

feat(typed): add optional Pydantic namespace wrapper (#354)

- Auto-format typed.py (ruff format)
- Add type: ignore[method-assign] to MagicMock assignments in test_typed.py
- Pass response= as keyword arg to HTTPError constructor in test_retry_decorator.py

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>