v3 M3: z.ai (GLM) provider — Anthropic-compatible poll from a pasted API key

ZaiProvider replaces the zai stub. It reaches z.ai's Anthropic-compatible
endpoint (default https://api.z.ai/api/anthropic) exactly like Claude Code with
ANTHROPIC_BASE_URL pointed at z.ai: a /v1/messages POST with a Bearer key. The
key + base URL come from the config the control panel's z.ai field writes
(providers.zai.base_url/.api_key) — no OAuth, no local files.

Two z.ai-specific cares: (1) static API key, no self-refresh; (2) the GLM Coding
Plan meters by prompts, so a 60s poll would drain quota — the provider
self-throttles to one network call per poll_interval_s (default 15 min) and
serves a cached status in between. Rate-limit parsing assumes z.ai proxies
Anthropic's unified headers (5h->s/sr, 7d->w/wr); if a real response lacks them
it still reports connected and logs the limit-ish headers it did return, so the
mapping can be finalized against a live key.

tools/probe_zai.py dumps a real z.ai response's headers (key via env, never
printed) to pin the exact header names. Graceful without a key: selecting z.ai
shows the blue theme + "no key", never crashes the loop. Registry: all three
providers now real; unknown ids fall back to StubProvider. +7 z.ai tests (mocked
transport: header mapping, auth, throttle, fallback); 120 passed, 2 Linux-only.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

clawdmeter.spec

@@ -41,6 +41,7 @@ hiddenimports = [
     'daemon.providers.base',
     'daemon.providers.anthropic',
     'daemon.providers.openai_codex',
+    'daemon.providers.zai',
     # The exact winrt media modules read_now_playing() pulls in.
     'winrt.windows.media',
     'winrt.windows.media.control',