feat: preset/profile system (core/refactor/security)

[bntvllnt]

Summary

Add a preset system that bundles MCP tools into profiles — agents load only the tools they need for their current task.

Motivation

• CKB's preset system is their best UX pattern: core (14 tools), review (19), refactor (19), full (80+)
• 15 tools is manageable, but as we grow (validate_change, enforce_architecture, etc.) tool discovery becomes a problem
• Different agent workflows need different tool subsets
• Reduces MCP tool registration overhead for focused tasks

Proposed Presets

Preset	Tools	Use Case
core	overview, file_context, search, hotspots, dependents	Basic exploration
review	core + detect_changes, impact_analysis, validate_change	Code review
refactor	core + dead_exports, forces, clusters, rename_symbol	Refactoring
architect	core + modules, forces, clusters, enforce_architecture	Architecture analysis
full	All tools	Everything

API

# MCP with preset
codebase-intelligence --preset review

# CLI: presets don't apply (all commands always available)

Acceptance Criteria

• --preset flag on MCP server
• 5 built-in presets
• Custom preset via config file
• Documented in MCP tools reference

Priority

Medium-term — UX improvement, becomes important as tool count grows.