docs: add per-repo detailed reports to permission modes research

Added Section 2 with detailed per-repo reports for all 8 projects:
- claude-code: 6-mode pipeline, dangerous patterns, YOLO classifier
- codex: OS sandboxing, exec policy engine, guardian auto-reviewer
- pi-agent-rust: O(1) policy snapshot, graduated rollout, WASM sandbox
- opencode: layered ruleset, wildcard matching, doom-loop detection
- oh-my-openagent: hook-chain guards, CC mode compat, write-before-read
- oh-my-pi: 3-tier/3-mode, critical bash patterns, ACP bridge
- codebuff: per-agent tool whitelist, propose-vs-execute
- dcg-core: current state analysis (has vs needs)

Fixed section numbering (1-9, no duplicates).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: quangdang46