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).

daemon/providers/__init__.py

@@ -0,0 +1,28 @@
+"""Provider registry (v3).
+
+get_provider(id) returns a Provider instance for the daemon to poll. Anthropic
+is real; OpenAI and z.ai return a StubProvider until M2/M3 land, so selecting
+them never crashes the loop.
+"""
+
+from __future__ import annotations
+
+from .base import Provider, ProviderStatus, StubProvider
+from .anthropic import AnthropicProvider
+
+# Brand accents / labels for the not-yet-implemented providers, so the stub still
+# carries the right theme hint to the watch once firmware theming lands.
+_STUB_META = {
+    "openai": ("OpenAI Codex", "10a37f"),
+    "zai": ("z.ai GLM", "3859ff"),
+}
+
+
+def get_provider(pid: str) -> Provider:
+    if pid == "anthropic":
+        return AnthropicProvider()
+    label, accent = _STUB_META.get(pid, (pid, "d97757"))
+    return StubProvider(pid, label=label, accent=accent)
+
+
+__all__ = ["Provider", "ProviderStatus", "StubProvider", "AnthropicProvider", "get_provider"]