feat(proxy): discover VS Code BYOK models dynamically

[romius]

Summary

Replace the hardcoded VS Code BYOK model catalog with profile-aware model discovery through the authenticated local CodeMie proxy. VS Code now receives the enabled models for the selected profile/project while retaining safe compatibility defaults for protocol routing and model-specific parameters that are not yet supplied by the backend catalog.

Changes

• Fetch, normalize, deduplicate, and deterministically order enabled models from /v1/llm_models?include_all=true.
• Resolve each model to Chat Completions, Responses, or Anthropic Messages using backend protocol metadata first and compatibility rules second; models that cannot be classified are omitted instead of receiving an unsafe fallback.
• Preserve the former static catalog behavior for reasoning efforts, token limits, zero-data-retention Responses mode, adaptive thinking, Anthropic bearer headers, and top_p: null.
• Keep backend-provided limits and capabilities authoritative when present.
• Update chatLanguageModels.json atomically while preserving unrelated providers, the CodeMie secret reference, and existing VS Code model settings.
• Add unit, integration, and opt-in live model certification coverage.

Impact

Before this change, VS Code exposed a fixed model list that could drift from the models enabled for a CodeMie profile. Reconnecting VS Code now refreshes the catalog from the selected profile without overwriting unrelated configuration.

Verification

• npm run typecheck — passed
• npm run lint — passed
• npm run build — passed
• npm run test:all — 2,957 passed, 8 skipped
• Live profile certification — 37 models discovered, 36 protocol-compatible, 130/130 model-effort combinations passed
• Certification report: VS Code live model results

One enabled model, deepseek-r1, remains intentionally unclassified because neither backend protocol metadata nor a verified compatibility rule is available.

Checklist

• Self-reviewed
• Manual testing performed
• Documentation updated (if needed)
• No breaking changes (or clearly documented)