feat: three-tier triage + vertical slice decomposition

[cohen-liel]

Replace binary simple/complex triage with SOLO/SMALL_TEAM/FULL_TEAM classification. Rewrite PM prompt to split by user flow instead of by layer — each task delivers a complete feature end-to-end, eliminating orphan components and missing UI wiring.

Key changes:

• orchestrator.py: _classify_tier() replaces _triage_is_simple()
• pm_agent.py: "split by USER FLOW" prompt, vertical slice example, complexity_tier param with max task validation
• config.py: reduced agent budgets (100→50 turns), reviewer timeout 300→600s, get_tier_adjusted_config()
• dag_executor_langgraph.py: MAX_DYNAMIC_TASKS 10→3, severity filter for quality roles, tier-aware limits
• skills_registry.py: truncation 2500→1500 chars, tier-aware injection
• contracts.py: tier-aware user message truncation, scope signal

Benchmarked on identical "build a task manager" prompt:

• v1 (before): 22 tasks, app broken, score 4.0/10
• v2 (tier system): 12 tasks, missing Create button, score 6.0/10
• v3 (vertical slicing): 8 tasks, everything works, score 7.4/10

Description

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• New agent (adds a specialist agent to the team)
• New runtime (adds support for a new AI provider)
• New template (adds a project template)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)

Related Issues

Component(s) Affected

• Dashboard UI
• DAG Engine
• Agent System
• Org Hierarchy
• CLI (create-hivemind)
• API / Backend
• Templates
• Documentation

Changes Made

Testing

• I have tested these changes locally
• Python syntax check passes (python3 -m py_compile)
• TypeScript compilation passes (npx tsc --noEmit)
• Frontend builds successfully (npx vite build)
• Existing tests still pass (python3 -m pytest tests/)

Screenshots

Checklist

• My code follows the project's code style
• I have added comments where necessary
• I have updated documentation if needed
• My changes don't introduce new warnings