feat(#60): implement link resolution service

- Create LinkResolutionService with workspace-scoped link resolution
- Resolve links by: exact title match, slug match, fuzzy title match
- Handle ambiguous matches (return null if multiple matches)
- Support batch link resolution with deduplication
- Comprehensive test suite with 19 tests, all passing
- 100% coverage of public methods
- Integrate service with KnowledgeModule

Closes #60 (KNOW-008)

apps/api/src/knowledge/knowledge.module.ts

@@ -3,11 +3,12 @@ import { PrismaModule } from "../prisma/prisma.module";
 import { AuthModule } from "../auth/auth.module";
 import { KnowledgeService } from "./knowledge.service";
 import { KnowledgeController } from "./knowledge.controller";
+import { LinkResolutionService } from "./services/link-resolution.service";
 
 @Module({
   imports: [PrismaModule, AuthModule],
   controllers: [KnowledgeController],
-  providers: [KnowledgeService],
-  exports: [KnowledgeService],
+  providers: [KnowledgeService, LinkResolutionService],
+  exports: [KnowledgeService, LinkResolutionService],
 })
 export class KnowledgeModule {}