v3 M1a: provider framework — config v2 + Provider abstraction (daemon)

Introduce the multi-provider seam on the host, behaviour-identical for Anthropic.

- config v2: `providers` (per-provider enable + creds), `active_provider`,
  `display_order`; v1 configs migrate transparently (anthropic enabled+active).
  New accessors: active_provider_id / provider_conf / enabled_providers.
- daemon/providers/: Provider ABC + normalized ProviderStatus (maps to the same
  s/sr/w/wr/st/tk/to/tc/tn BLE fields), AnthropicProvider (wraps the existing
  OAuth+poll+local-usage logic), StubProvider for openai/zai until M2/M3, and a
  get_provider() registry.
- poll loop: polls the config-selected active provider each cycle and tags the
  payload with `pv` (the brand-theme id the watch will wear). Watch->PC
  `{"cmd":"prov","id":".."}` persists the active provider and repolls at once.
- clawdmeter.spec: bundle daemon.providers for the frozen exe.
- test: 7 new provider/config tests; fix a stale start_notify count assertion
  (the M2 command channel means both REQ and CMD subscriptions are attempted).

Verified live: config loads as v2, active provider resolves to AnthropicProvider,
a real poll returns ok=True (s=53%, w=5%); full suite 87 passed (+7 new).

clawdmeter.spec

@@ -36,6 +36,10 @@ hiddenimports = [
     'daemon.server',
     'daemon.panel',
     'daemon.ha_client',
+    # v3 provider package (registry + providers are lazy-imported in the loop).
+    'daemon.providers',
+    'daemon.providers.base',
+    'daemon.providers.anthropic',
     # The exact winrt media modules read_now_playing() pulls in.
     'winrt.windows.media',
     'winrt.windows.media.control',