fix(providers): 修复火山 Plan 模型请求与 ASR 服务接入

[MikuHello]

Problem and behavior

Fixes #1062 and #1063. Ark's default f32 temperature was expanded to 0.30000001192092896 in request JSON, causing verified Plan GLM models to reject otherwise valid requests. Text requests now preserve the configured decimal representation while retaining existing optional-temperature and protocol omission rules.

Model catalog 404s now explain that the current endpoint cannot provide a list, preserve manual model entry, and remain independent of inference validation. Coding Plan's existing catalog path is unchanged. Ark's form explains that text generation models are required; no static catalog is presented as a live response and no standard-billing fallback is introduced.

Volcengine ASR has an explicit Standard / Agent Plan service selection. Existing configurations keep the standard endpoint and auth mode; Agent Plan uses the dedicated /plan/sauc/bigmodel_async endpoint and API-key authentication. Service selection is persisted per channel through Core, Tauri and Linux adapters. Unknown service values fail instead of falling back. A small external connection boundary allows deterministic tests of real WebSocket handshakes through open_session.

Validation

• Core full suite (793 unit tests passed, 1 ignored, plus integration tests), frontend suite, independent backend contract/TLS tests, and 35 Tauri credential tests passed.
• Actual HTTP regressions cover default/custom decimal temperatures, protocol behavior and catalog/channel preservation.
• Actual loopback WebSocket handshake regression covers Standard App ID + Token, Standard API key, and Agent Plan paths/headers; a deliberate old-endpoint mutation is detected.
• Live Agent Plan: glm-5.3-flash and ark-code-latest validation, nonstreaming polish and streaming polish passed.
• Live Coding Plan: catalog, ark-code-latest and glm-5-3-flash-260828 validation/nonstreaming/streaming polish passed.
• Live Agent ASR through the shared engine returned 明天下午3点开会，请准时参加。 from synthetic 16 kHz mono speech.
• macOS INSTALL=0 ./scripts/build-mac.sh passed; launched the resulting 2.0.0-Beta.1 app and checked its signature/resources.
• Desktop Agent catalog failure copy, manual model validation, Agent ASR validation, saved service/model/key-presence after full restart, and retained Standard auth mode when switching back all passed. Microphone and Accessibility show granted; global hotkey listener is installed.
• Physical microphone-to-cursor dictation is reserved for the requester’s final acceptance and is not claimed as tested here. Coding desktop catalog interaction and multiple-channel desktop isolation were not exercised; their provider/Core regression coverage and live API results are listed above.

Linux/Windows/Android device smoke tests and ordinary-service live ASR with a separate ordinary account have not been performed. Existing unrelated rustfmt failures in the baseline's OrcaRouter tests and TLS identity tests were left unchanged. No dependency versions, CI, hooks or release processes were changed.