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/entities/personality.entity.ts

@@ -0,0 +1,15 @@
+import { Personality as PrismaPersonality, FormalityLevel } from "@prisma/client";
+
+export class Personality implements PrismaPersonality {
+  id!: string;
+  workspaceId!: string;
+  name!: string;
+  description!: string | null;
+  tone!: string;
+  formalityLevel!: FormalityLevel;
+  systemPromptTemplate!: string;
+  isDefault!: boolean;
+  isActive!: boolean;
+  createdAt!: Date;
+  updatedAt!: Date;
+}