feat: model-router MCP cartridge — intelligent model switching

Analyses tasks and recommends optimal Claude model (opus/sonnet/haiku).
Four MCP tools:
- classify_task: complexity analysis with keyword + heuristic scoring
- plan_delegation: generates step-by-step instructions for cheaper model
- review_output: Opus reviews delegated work (APPROVED/NEEDS_REVISION/FAILED)
- estimate_cost: relative cost comparison across models + delegation savings

Plan-and-delegate pattern: Opus plans (10% tokens) → Haiku executes
(90% tokens) → Opus reviews (10% tokens) = ~25% of Opus-only cost.

Also installed as Claude Code skill at ~/.claude/skills/model-route.md
for /model-route <task> usage.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath