feat(flyer-import): integrate AI-based flyer parsing with image support

- Add support for PNG, JPEG, and WebP image formats in flyer import
- Replace external importer service with internal AI-based parsing pipeline
- Add new services: TextExtractorService, AiFlyerParserService, FlyerNormalizerService
- Integrate Mistral AI, pdf-parse, and tesseract.js dependencies
- Add quality confidence indicators and warning panels in Flutter UI
- Update package.json with new dependencies and transform ignore patterns
- Add documentation for flyer importer system
- Add Kilo AI planning file for Happy Island project

BREAKING CHANGE: Flyer import now uses internal AI parsing instead of external importer service

backend/src/flyer-import/flyer-import.module.ts

@@ -2,10 +2,18 @@ import { Module } from '@nestjs/common';
 import { PrismaModule } from '../prisma/prisma.module';
 import { FlyerImportController } from './flyer-import.controller';
 import { FlyerImportService } from './flyer-import.service';
+import { TextExtractorService } from './services/text-extractor.service';
+import { AiFlyerParserService } from './services/ai-flyer-parser.service';
+import { FlyerNormalizerService } from './services/flyer-normalizer.service';
 
 @Module({
   imports: [PrismaModule],
   controllers: [FlyerImportController],
-  providers: [FlyerImportService],
+  providers: [
+    FlyerImportService,
+    TextExtractorService,
+    AiFlyerParserService,
+    FlyerNormalizerService,
+  ],
 })
 export class FlyerImportModule {}