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/knowledge/services/link-sync.service.ts

@@ -0,0 +1,201 @@
+import { Injectable } from "@nestjs/common";
+import { PrismaService } from "../../prisma/prisma.service";
+import { LinkResolutionService } from "./link-resolution.service";
+import { parseWikiLinks, WikiLink } from "../utils/wiki-link-parser";
+
+/**
+ * Represents a backlink to a knowledge entry
+ */
+export interface Backlink {
+  id: string;
+  sourceId: string;
+  targetId: string;
+  linkText: string;
+  displayText: string;
+  positionStart: number;
+  positionEnd: number;
+  resolved: boolean;
+  context: string | null;
+  createdAt: Date;
+  source: {
+    id: string;
+    title: string;
+    slug: string;
+  };
+}
+
+/**
+ * Represents an unresolved wiki link
+ */
+export interface UnresolvedLink {
+  id: string;
+  sourceId: string;
+  targetId: string | null;
+  linkText: string;
+  displayText: string;
+  positionStart: number;
+  positionEnd: number;
+  resolved: boolean;
+  context: string | null;
+  createdAt: Date;
+  source: {
+    id: string;
+    title: string;
+    slug: string;
+  };
+}
+
+/**
+ * Service for synchronizing wiki-style links in knowledge entries
+ *
+ * Responsibilities:
+ * - Parse content for wiki links
+ * - Resolve links to knowledge entries
+ * - Store/update link records
+ * - Handle orphaned links
+ */
+@Injectable()
+export class LinkSyncService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly linkResolver: LinkResolutionService
+  ) {}
+
+  /**
+   * Sync links for a knowledge entry
+   * Parses content, resolves links, and updates the database
+   *
+   * @param workspaceId - The workspace scope
+   * @param entryId - The entry being updated
+   * @param content - The markdown content to parse
+   */
+  async syncLinks(
+    workspaceId: string,
+    entryId: string,
+    content: string
+  ): Promise<void> {
+    // Parse wiki links from content
+    const parsedLinks = parseWikiLinks(content);
+
+    // Get existing links for this entry
+    const existingLinks = await this.prisma.knowledgeLink.findMany({
+      where: {
+        sourceId: entryId,
+      },
+    });
+
+    // Resolve all parsed links
+    const linkCreations: Array<{
+      sourceId: string;
+      targetId: string | null;
+      linkText: string;
+      displayText: string;
+      positionStart: number;
+      positionEnd: number;
+      resolved: boolean;
+    }> = [];
+
+    for (const link of parsedLinks) {
+      const targetId = await this.linkResolver.resolveLink(
+        workspaceId,
+        link.target
+      );
+
+      linkCreations.push({
+        sourceId: entryId,
+        targetId: targetId,
+        linkText: link.target,
+        displayText: link.displayText,
+        positionStart: link.start,
+        positionEnd: link.end,
+        resolved: targetId !== null,
+      });
+    }
+
+    // Determine which existing links to keep/delete
+    // We'll use a simple strategy: delete all existing and recreate
+    // (In production, you might want to diff and only update changed links)
+    const existingLinkIds = existingLinks.map((link) => link.id);
+
+    // Delete all existing links and create new ones in a transaction
+    await this.prisma.$transaction(async (tx) => {
+      // Delete all existing links
+      if (existingLinkIds.length > 0) {
+        await tx.knowledgeLink.deleteMany({
+          where: {
+            sourceId: entryId,
+            id: {
+              in: existingLinkIds,
+            },
+          },
+        });
+      }
+
+      // Create new links
+      for (const linkData of linkCreations) {
+        await tx.knowledgeLink.create({
+          data: linkData,
+        });
+      }
+    });
+  }
+
+  /**
+   * Get all backlinks for an entry
+   * Returns entries that link TO this entry
+   *
+   * @param entryId - The target entry
+   * @returns Array of backlinks with source entry information
+   */
+  async getBacklinks(entryId: string): Promise<Backlink[]> {
+    const backlinks = await this.prisma.knowledgeLink.findMany({
+      where: {
+        targetId: entryId,
+        resolved: true,
+      },
+      include: {
+        source: {
+          select: {
+            id: true,
+            title: true,
+            slug: true,
+          },
+        },
+      },
+      orderBy: {
+        createdAt: "desc",
+      },
+    });
+
+    return backlinks as Backlink[];
+  }
+
+  /**
+   * Get all unresolved links for a workspace
+   * Useful for finding broken links or pages that need to be created
+   *
+   * @param workspaceId - The workspace scope
+   * @returns Array of unresolved links
+   */
+  async getUnresolvedLinks(workspaceId: string): Promise<UnresolvedLink[]> {
+    const unresolvedLinks = await this.prisma.knowledgeLink.findMany({
+      where: {
+        source: {
+          workspaceId,
+        },
+        resolved: false,
+      },
+      include: {
+        source: {
+          select: {
+            id: true,
+            title: true,
+            slug: true,
+          },
+        },
+      },
+    });
+
+    return unresolvedLinks as UnresolvedLink[];
+  }
+}