Simplifies routing logic by delegating all provider/mapping/proxy
decisions to FallbackHandler. Previously, the route checked for
provider/mapping availability before calling the handler, then
FallbackHandler performed the same checks again.
Changes:
- Remove model extraction and provider checking from route (lines 182-201)
- Route now only checks if request is POST with /models/ path
- FallbackHandler handles provider -> mapping -> proxy fallback
- Remove unused internal/util import
Benefits:
- Eliminates duplicate checks (addresses PR review feedback #2)
- Centralizes all provider/mapping logic in FallbackHandler
- Reduces routing code by ~20 lines
- Aligns with how other /api/provider routes work
Performance: No impact (checks still happen once in FallbackHandler)
bfc738b76a