feat: configurable report language (default zh-CN)

Add providers.yaml `language` / Action input `language`; prompts and
published summary/inline honor it. Soften fail-closed messaging when
models 429; prefer cohere/nvidia in the first-3 parallel set for dogfood.

README.md

@@ -27,25 +27,34 @@ Allowlists / Gitea-on-github.com limitations: [`docs/remote-uses.md`](docs/remot
 ## Providers YAML
 
 ```yaml
+language: zh-CN               # report language: zh-CN | en | … (prompts + published comments)
+
 providers:
   openrouter:                 # only include providers you configure
     key: OPENROUTER_API_KEY   # free-form secret/env name — pick any
     protocol: openai          # openai | openai-completions | openai-responses | anthropic
     # base_url: optional (defaults exist for openrouter / anthropic / openai)
     models:
-      - google/gemma-4-31b-it:free
-      - google/gemma-4-26b-a4b-it:free
       - cohere/north-mini-code:free
       - nvidia/nemotron-3-nano-omni-30b-a3b-reasoning:free
+      - google/gemma-4-31b-it:free
 ```
 
 | Field | Meaning |
 | --- | --- |
+| `language` | Report language for model prose + summary/inline comments (`zh-CN`, `en`, …). Alias: `report_language`. |
 | `key` | **Free-form** name of the GitHub secret / env var holding the API key. **No** required `gatekeep_` prefix. |
 | `protocol` | `openai` \| `openai-completions` \| `openai-responses` \| `anthropic` |
 | `models` | Names to use (validated against the provider’s model list API at runtime) |
 | `base_url` | Optional; known provider ids get defaults |
 
+### Report language
+
+- **This repo’s defaults:** `language: zh-CN` in `defaults/providers.yaml`.
+- **Override without editing YAML:** Action input `language: en` (or `zh-CN`).
+- Resolution order: Action input `language` → YAML `language` / `report_language` → `en`.
+- JSON field names and enums stay English; human-facing prose follows the configured language.
+
 Mix providers in one review by listing several entries. Secrets are read from the **workflow step `env`** using each entry’s `key` name.
 
 Example suggestion only (still free-form): `key: gatekeep_openrouter` is fine if you named your secret that — not required.