feat: Add KB knowledge base series skills

- kb-link-parser: Multi-platform URL parser (Bilibili, YouTube, Zhihu)
- kb-bilibili-metadata: Bilibili video/article/up主 metadata extractor
- kb-zhihu-metadata: Zhihu question/answer/user metadata extractor
- kb-bilibili-content: Bilibili video download and content extraction
- kb-ocr-processor: OCR text extraction from video frames
- kb-deep-analyzer: AI-powered deep content analysis
- kb-workflow: Workflow orchestration (inbox, archive, subscriptions, report)

Also add:
- ARCHITECTURE_FLOWCHART.md: System architecture diagrams
- DETAILED_DESIGN.md: Complete design documentation

skills/kb-workflow/knowledge-base/reports/report_20260210.json

@@ -0,0 +1,36 @@
+{
+  "generated_at": "2026-02-10T12:13:35.989689",
+  "period": "daily",
+  "start_date": "2026-02-09T12:13:35.989689",
+  "summary": {
+    "total_items_inbox": 0,
+    "total_archived": 0,
+    "items_by_stage": {
+      "pending": {
+        "count": 0,
+        "path": "/home/admin/.openclaw/workspace/skills/kb-workflow/knowledge-base/pending"
+      },
+      "metadata": {
+        "count": 0,
+        "path": "/home/admin/.openclaw/workspace/skills/kb-workflow/knowledge-base/metadata"
+      },
+      "content": {
+        "count": 0,
+        "path": "/home/admin/.openclaw/workspace/skills/kb-workflow/knowledge-base/content"
+      },
+      "analyzed": {
+        "count": 0,
+        "path": "/home/admin/.openclaw/workspace/skills/kb-workflow/knowledge-base/analyzed"
+      }
+    }
+  },
+  "processing_stats": {
+    "pending": 0,
+    "metadata": 0,
+    "content": 0,
+    "analyzed": 0
+  },
+  "recommendations": [
+    "📭 收件箱为空，暂无待处理内容"
+  ]
+}