Selectively sync upstream provider form fixes

[seakee]

Summary

• Add show and hide controls for provider API key fields while preserving the current provider edit page layout.
• Prevent browser autofill on provider secret inputs with new-password autocomplete behavior.
• Tighten provider edit route index parsing and keep OpenAI auth-index-only key entries testable.
• Intentionally skip the upstream Provider workbench replacement, Bun migration, and compatibility-reducing parser cleanups.

Testing

• npm run type-check
• npm run test
• npm run build
• npm run lint (passes with one existing MonitoringCenterPage fast-refresh warning)
• go test ./... in usage-service
• git diff --check