GCC v2: lean git-backed memory system

[faugustdev]

Summary

• New storage format: index.yaml replaces 6 markdown files. Stores hash + intent + optional note (~50 tokens/entry vs ~500 in v1)
• 4 new utility scripts: gcc_commit.sh, gcc_context.sh, gcc_bridge.sh, gcc_cleanup.sh
• Dual mode: auto-detects git repo (lean index) or falls back to standalone (v1-compatible markdown)
• aiyoucli bridge: auto-feeds commit data to vector memory when available
• Updated docs: README, SKILL.md, file_formats.md, sample_session.md rewritten for v2

Breaking Changes

• index.yaml replaces commit.md, log.md, metadata.yaml as primary storage
• gcc_init.sh now creates v2 structure by default
• Use gcc_init.sh --upgrade to migrate from v1 (backs up old files)

New Scripts

Script	Purpose
gcc_commit.sh	Real git commit + lean index entry
gcc_context.sh	Reconstruct context from hashes (--summary, --last N, --hash, --decisions)
gcc_bridge.sh	Feed commit data to aiyoucli vector memory
gcc_cleanup.sh	TTL-based worktree cleanup + index pruning

Test plan

• Init in git mode (detects branch + last hash)
• Init in standalone mode (markdown fallback)
• 3 commits with special characters (", :, \)
• Context reconstruction: --summary, --last N, --hash, --decisions, --full
• Bridge status check
• Cleanup dry-run + prune-index
• Initial commit edge case (no parent to diff)
• v1 upgrade path (--upgrade flag)