1. enrichItem: add Logger.warn on COS errors instead of silent catch
2. getTrend: add 15s timeout fallback for AI analysis
3. buildDailySeries: use local date strings to avoid UTC timezone shift
4. detectSourceType: use lazy regex .+? to prevent ReDoS on long texts
5. sortBy: validate against whitelist, reject invalid values
6. PaginationDto visibility/ownerType: already handled via @Query params
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
B7 Feynman evaluation: POST /ai-analysis/feynman
B8 Knowledge import: replaces DocumentImport setTimeout mock with AI
B9 Review card generation: POST /reviews/generate-cards
B10 Learning trend analysis: GET /activity/trend
4 workflows, 4 prompts, 4 schemas, all registered in AiModule.
AiAnalysisRepository made generic to handle varied result shapes.
DocumentImportService now calls KnowledgeImportWorkflow + saves to DB.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
