Rebuild on current upstream: drop redundant SPH/throttle, keep shared-session re-login

[johanzander]

Summary

master had drifted behind current upstream home-assistant/core in ways it shouldn't have — this rebuilds on vendor-sync (a clean current snapshot of upstream's growatt_server component) and re-applies only what's genuinely still needed.

Dropped (now redundant with upstream):

• SPH device support (sph.py + wiring in coordinator/services/sensor) — duplicated your own home-assistant/core#165314, merged 2026-03-16. Upstream's canonical version is used instead.
• throttle.py's ApiThrottleManager — verified it was never actually wired into the setup flow (_handle_throttled_setup had zero call sites, ApiThrottleManager was never instantiated anywhere). Dead code with its own test file. Dropped, along with tests/test_throttle.py and the now-unused mock_throttle_manager autouse fixture / no_throttle_mock marker.
• Everything else — took upstream's more current version wholesale (translation_key-based exceptions, the periodic new/removed-device auto-discovery scanner, general refactors, diagnostics.py).

Kept, because it's real and still load-bearing:

• Every GrowattCoordinator for a config entry now shares one authenticated API instance via config_entry.runtime_data.api, instead of each coordinator creating and logging into its own. Upstream's coordinator currently calls api.login() on every single update cycle for Classic API — with N devices that's N independent logins every scan interval, which is very likely the actual root cause of the rate-limiting problems this integration has fought historically.
• GrowattCoordinator._async_re_login: reactive re-authentication on session expiry (detected via JSONDecodeError — the server returns an HTML login page instead of JSON), guarded by a shared asyncio.Lock + 60s cooldown (runtime_data.login_lock / last_login_time) so concurrent coordinators don't all re-login at once.

Also fixed: two except ValueError, TypeError:-style syntax errors (invalid Python 3 syntax) that are present in upstream home-assistant/core's dev branch itself right now — found because the file wouldn't compile otherwise. Worth reporting upstream separately.

Test plan

• ruff check passes clean on every changed file.
• python -m py_compile passes clean on every changed file (also how the two upstream syntax errors were caught).
• Not run: the pytest-homeassistant-custom-component suite. This dev environment's package index caps at homeassistant==2025.1.4, which predates this component's current structure (no AUTH_API_TOKEN, etc.) — confirmed this is a pre-existing environment limitation, not something introduced here, by running unmodified master against the same environment and getting an identical import failure. Please run the real test suite locally before merging.

[johanzander]

Superseded by a cleaner split: #35