fix: revert unsupported AFC config and add diagnostic logging for VIN decode (refs #231)

- Remove AutomaticFunctionCallingConfig(max_remote_calls=3) which caused
  pydantic validation error on the installed google-genai version
- Log full Gemini raw JSON response in OCR engine for debugging
- Add engine/transmission to backend raw values log
- Add hasTrim/hasEngine/hasTransmission to decode success log

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/features/vehicles/api/vehicles.controller.ts

@@ -416,7 +416,10 @@ export class VehiclesController {
         userId,
         hasYear: !!decodedData.year.value,
         hasMake: !!decodedData.make.value,
-        hasModel: !!decodedData.model.value
+        hasModel: !!decodedData.model.value,
+        hasTrim: !!decodedData.trimLevel.value,
+        hasEngine: !!decodedData.engine.value,
+        hasTransmission: !!decodedData.transmission.value,
       });
 
       return reply.code(200).send(decodedData);

backend/src/features/vehicles/domain/vehicles.service.ts

@@ -679,7 +679,8 @@ export class VehiclesService {
     logger.debug('VIN decode raw values', {
       vin: response.vin,
       year: sourceYear, make: sourceMake, model: sourceModel,
-      trim: sourceTrim, confidence: response.confidence
+      trim: sourceTrim, engine: sourceEngine, transmission: sourceTransmission,
+      confidence: response.confidence
     });
 
     // Year is always high confidence if present (exact numeric match)

ocr/app/engines/gemini_engine.py

@@ -398,7 +398,12 @@ class GeminiEngine:
                     vin,
                 )
 
-            logger.info("Gemini decoded VIN %s (confidence=%.2f)", vin, raw.get("confidence", 0))
+            logger.info(
+                "Gemini decoded VIN %s (confidence=%.2f) raw=%s",
+                vin,
+                raw.get("confidence", 0),
+                json.dumps(raw, default=str),
+            )
 
             return VinDecodeResult(
                 year=resolved_year if resolved_year else raw.get("year"),