Add local skill metadata index

[hwrcome]

Summary

This PR adds a lightweight local Skill/SOP index to the system context.

Previously, fresh tasks could only discover reusable SOPs if they were manually listed in memory/global_mem_insight.txt. This made cross-task reuse dependent on agents remembering to update the L1 index.

This change scans top-level memory/*.md files, extracts lightweight metadata, and injects a [Skill/SOP Index] into the system context. The agent is then instructed to read a relevant SOP before acting.

Changes

• Add local Skill/SOP metadata extraction from memory/*.md
• Inject [Skill/SOP Index] into global memory context
• Update Chinese and English system prompts to prefer relevant local skills/SOPs before solving from scratch

Validation

Verified with a fresh task where:

• the user input did not mention code_review_principles.md
• memory/global_mem_insight.txt did not contain code_review_principles
• the fresh task still read code_review_principles.md at Turn 1

This confirms the generated Skill/SOP index works independently of conversation history or manual L1 indexing.