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/dto/create-personality.dto.ts

@@ -0,0 +1,43 @@
+import { IsString, IsIn, IsOptional, IsBoolean, MinLength, MaxLength } from "class-validator";
+
+export const FORMALITY_LEVELS = [
+  "VERY_CASUAL",
+  "CASUAL",
+  "NEUTRAL",
+  "FORMAL",
+  "VERY_FORMAL",
+] as const;
+
+export type FormalityLevel = (typeof FORMALITY_LEVELS)[number];
+
+export class CreatePersonalityDto {
+  @IsString()
+  @MinLength(1)
+  @MaxLength(100)
+  name!: string;
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  description?: string;
+
+  @IsString()
+  @MinLength(1)
+  @MaxLength(50)
+  tone!: string;
+
+  @IsIn(FORMALITY_LEVELS)
+  formalityLevel!: FormalityLevel;
+
+  @IsString()
+  @MinLength(10)
+  systemPromptTemplate!: string;
+
+  @IsOptional()
+  @IsBoolean()
+  isDefault?: boolean;
+
+  @IsOptional()
+  @IsBoolean()
+  isActive?: boolean;
+}

apps/api/src/personalities/dto/index.ts

@@ -0,0 +1,2 @@
+export * from "./create-personality.dto";
+export * from "./update-personality.dto";

apps/api/src/personalities/dto/update-personality.dto.ts

@@ -0,0 +1,4 @@
+import { PartialType } from "@nestjs/mapped-types";
+import { CreatePersonalityDto } from "./create-personality.dto";
+
+export class UpdatePersonalityDto extends PartialType(CreatePersonalityDto) {}