feat: add OpenRouter quantization filter to exclude low-bit providers (rebased)

[roomote]

Related GitHub Issue

Closes: #11325

Description

This PR attempts to address Issue #11325 by re-implementing the feature from PR #11366 on a clean branch from main, since that PR had unresolvable merge conflicts due to significant codebase changes since it was created.

Changes:

1. Schema (packages/types/src/provider-settings.ts): Added openRouterExcludeLowQuantization: z.boolean().optional() to the openRouterSchema.

2. Handler (src/api/providers/openrouter.ts): Added a buildProviderOptions() private method that centralizes provider option construction for both createMessage() and completePrompt(). When the setting is enabled, provider.quantizations is set to ["fp16", "bf16", "fp8", "int8"], restricting to higher-precision providers. This also combines with the existing specific provider routing when both are set.

3. UI (webview-ui/src/components/settings/providers/OpenRouter.tsx): Added a checkbox labeled "Exclude low-bit quantization (FP4/FP6/Int4)" with a description explaining the CJK encoding fix.

4. i18n: Added English translations and fallback values for all 17 non-English locales.

Test Procedure

• Added 6 new tests in src/api/providers/__tests__/openrouter.spec.ts covering buildProviderOptions():
  • Returns undefined when no specific provider and no quantization filter
  • Returns provider routing when specific provider is set
  • Returns quantizations when excludeLowQuantization is enabled
  • Combines specific provider and quantization filter correctly
  • Returns undefined when specific provider is the default "[default]"
  • Returns undefined when excludeLowQuantization is false
• All 30 tests pass: cd src && npx vitest run api/providers/__tests__/openrouter.spec.ts
• Translation check passes: node scripts/find-missing-translations.js

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Testing: New and/or updated tests have been added to cover my changes.
• Documentation Impact: No documentation updates required.
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Documentation Updates

• No documentation updates are required.

Additional Notes

The setting defaults to off, preserving existing behavior. When enabled, it uses the OpenRouter documented provider.quantizations API field to restrict routing to higher-precision providers only. Feedback and guidance are welcome.

Interactively review PR in Roo Code Cloud

[jongleeat]

@roomote
You used english for check-translation ci. Could you fix proper language for each i18n/locales translation ?

[roomote]

Fixaroo   See task

Translated the excludeLowQuantization label and description into proper native language for all 17 non-English locales. Translation validation script passes cleanly.

_{View commit | Revert commit}

[jongleeat]

@roomote
This PR is now on "Review required". Please assign a reviewer to merge this pull request.

[roomote]

Fixaroo   See task

Marked this PR as ready for review. All 30 tests pass and translations are complete.