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-ocr-processor/SKILL.md

@@ -0,0 +1,43 @@
+# KB OCR Processor Skill
+
+**kb-ocr-processor** - Extract text from video frames using OCR.
+
+## Features
+
+- Batch frame processing
+- PaddleOCR/Tesseract support
+- Confidence scoring
+- Text merging
+
+## Commands
+
+```bash
+# Process frames
+python ocr_processor.py --input ./frames/ --output ocr.json
+
+# With custom FPS
+python ocr_processor.py --input ./frames/ --fps 0.1 --output ocr.json
+```
+
+## Output
+
+```json
+{
+  "success": true,
+  "data": {
+    "frames": {
+      "frame_0001.jpg": {
+        "texts": [{"text": "字幕", "confidence": 0.95}]
+      }
+    },
+    "merged_text": "合并的字幕文本..."
+  }
+}
+```
+
+## Installation
+
+```bash
+cp -r kb-ocr-processor/ ~/skills/
+pip install -r requirements.txt
+```