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-link-parser/SKILL.md

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+# KB Link Parser Skill
+
+**kb-link-parser** - Extract and resolve IDs from various platform URLs.
+
+## Features
+
+- Multi-platform support: Bilibili, YouTube, Zhihu
+- Short link detection: b23.tv and other short links
+- Multiple content types: video, article, up主, playlist, collection
+- Batch processing from file
+- JSON output format
+
+## Commands
+
+```bash
+# Parse single URL
+python link-parser.py --url "https://www.bilibili.com/video/BV1xx411c7mD"
+
+# Batch processing
+python link-parser.py --batch urls.txt --output results.json
+
+# Output format
+python link-parser.py --url "..." --format json
+```
+
+## Output
+
+```json
+{
+  "success": true,
+  "data": {
+    "platform": "bilibili",
+    "type": "video",
+    "id": "BV1xx411c7mD"
+  }
+}
+```
+
+## Installation
+
+```bash
+cp -r kb-link-parser/ ~/skills/
+```