docs(agents): update AGENTS.md with skill-mcp feature documentation

- Update timestamp to 2026-01-02T00:10:00+09:00 and commit hash b0c39e2
- Add 'Add skill' and 'Skill MCP' sections to WHERE TO LOOK table
- Add 'Self-planning for complex tasks' anti-pattern to ANTI-PATTERNS
- Update complexity hotspots with current accurate line counts (src/index.ts 723, src/cli/config-manager.ts 669, etc.)
- Add SKILL MCP MANAGER and BUILTIN SKILLS sections to src/features/AGENTS.md
- Document skill-mcp-manager lifecycle and builtin-skills location
- Update src/tools/AGENTS.md to include skill and skill-mcp tool categories
- Update testing note to reference 360+ tests passing
- Add Skill MCP note to NOTES section describing YAML frontmatter MCP config

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/tools/AGENTS.md

@@ -29,6 +29,8 @@ tools/
 │   ├── storage.ts      # File I/O operations
 │   ├── utils.ts        # Formatting, filtering
 │   └── tools.ts        # Tool implementations
+├── skill/              # Skill loading and execution
+├── skill-mcp/          # Skill-embedded MCP invocation
 ├── slashcommand/       # Slash command execution
 └── index.ts            # builtinTools export
 ```
@@ -45,6 +47,7 @@ tools/
 | Multimodal | look_at | PDF/image analysis via Gemini |
 | Terminal | interactive_bash | Tmux session control |
 | Commands | slashcommand | Execute slash commands |
+| Skills | skill, skill_mcp | Load skills, invoke skill-embedded MCPs |
 | Agents | call_omo_agent | Spawn explore/librarian |
 
 ## HOW TO ADD A TOOL