feat(#82): implement Personality Module

- Add Personality model to Prisma schema with FormalityLevel enum
- Create migration and seed with 6 default personalities
- Implement CRUD API with TDD approach (97.67% coverage)
  * PersonalitiesService: findAll, findOne, findDefault, create, update, remove
  * PersonalitiesController: REST endpoints with auth guards
  * Comprehensive test coverage (21 passing tests)
- Add Personality types to shared package
- Create frontend components:
  * PersonalitySelector: dropdown for choosing personality
  * PersonalityPreview: preview personality style and system prompt
  * PersonalityForm: create/edit personalities with validation
  * Settings page: manage personalities with CRUD operations
- Integrate with Ollama API:
  * Support personalityId in chat endpoint
  * Auto-inject system prompt from personality
  * Fall back to default personality if not specified
- API client for frontend personality management

All tests passing with 97.67% backend coverage (exceeds 85% requirement)

apps/api/src/personalities/personalities.module.ts

@@ -0,0 +1,13 @@
+import { Module } from "@nestjs/common";
+import { PrismaModule } from "../prisma/prisma.module";
+import { AuthModule } from "../auth/auth.module";
+import { PersonalitiesService } from "./personalities.service";
+import { PersonalitiesController } from "./personalities.controller";
+
+@Module({
+  imports: [PrismaModule, AuthModule],
+  controllers: [PersonalitiesController],
+  providers: [PersonalitiesService],
+  exports: [PersonalitiesService],
+})
+export class PersonalitiesModule {}