fix(console): proxy inference without parsing

[thdxr]

Summary

• forward legacy /zen generation requests directly to the corresponding /inference route
• preserve the native request body stream without calling request.json()
• retain legacy public-key, client-IP, and request-ID header compatibility

Scope

One source file changed with a guarded early return. Existing legacy implementation remains untouched as fallback. Model-list and non-inference routes are unchanged.

Checks

• console app typecheck
• pre-push workspace typecheck (30 tasks)

[thdxr]

Closing: this bypasses legacy settlement and behavior, which must remain unchanged.