feat: add vision core, feishu watchdog, and enhanced system prompts

[pandyzhou]

Summary

This PR brings two related enhancements to the GenericAgent project:

1. Vision Core & Feishu Watchdog (075dab4)

• vision_core.py (250 lines): A new ask_vision function for multimodal vision queries, with image encoding utilities (image_to_data_url, _encode_png_bytes, _build_user_message).
• feishu_watchdog.py (51 lines): A watchdog process to monitor and auto-restart the Feishu/Lark bot integration, improving service reliability.
• tests/test_vision_core.py (138 lines): Unit tests covering the vision core functionality.
• requirements.txt: Project dependencies including Pillow, requests, etc.
• Updated vision_sop.md and fsapp.py (connection retry logic, watchdog integration).

2. System Prompts Overhaul (f4b4c95)

• Expanded sys_prompt.txt and sys_prompt_en.txt with new sections: Personality, Values, Interaction Style, and Coding Guidelines.
• Minor adjustment in fsapp.py for default LLM selection.

Files Changed

Type	File
New	vision_core.py
New	frontends/feishu_watchdog.py
New	tests/test_vision_core.py
New	requirements.txt
Modified	assets/sys_prompt.txt
Modified	assets/sys_prompt_en.txt
Modified	frontends/fsapp.py
Modified	memory/vision_sop.md

Stats: +786 / -12 across 8 files