fix: preserve OpenAI compatibility upstream model metadata

[YamonBot]

Closes #111

Why

Home synthesizes OpenAI-compatible aliases into home_config_models, but currently retains only the client-facing alias ID and drops the configured upstream model name. Dynamic service-key dispatch therefore forwards the alias literally to the provider.

What changed

• preserve OpenAICompatibilityModel.Name in synthesized registry.ModelInfo
• add a focused regression proving fractalops-coding retains upstream glm-5.3 metadata

Verification

• go test ./internal/watcher/synthesizer ./internal/cliproxy/auth
• git diff --check origin/dev...HEAD

This is separate from OAuth response-model force-mapping; it restores request-time alias-to-upstream resolution for OpenAI-compatible API-key providers.

[YamonBot]

@hkfires This is blocking a live Home service-key deployment. The production change is one metadata field and the focused tests pass locally; a maintainer approval for fork CI/review would help us validate and ship it upstream without carrying a downstream fork.