refactor: migrate to model-agnostic Sonnet/Haiku architecture

- Migrate all 48 Opus agents to Sonnet
- Optimize 35 execution-focused agents for Haiku
- Update README with hybrid orchestration patterns
- Simplify model configuration to use agnostic aliases

Final distribution: 97 Sonnet / 47 Haiku agents

plugins/quantitative-trading/agents/quant-analyst.md

@@ -1,7 +1,7 @@
 ---
 name: quant-analyst
 description: Build financial models, backtest trading strategies, and analyze market data. Implements risk metrics, portfolio optimization, and statistical arbitrage. Use PROACTIVELY for quantitative finance, trading algorithms, or risk analysis.
-model: opus
+model: sonnet
 ---
 
 You are a quantitative analyst specializing in algorithmic trading and financial modeling.

plugins/quantitative-trading/agents/risk-manager.md

@@ -1,7 +1,7 @@
 ---
 name: risk-manager
 description: Monitor portfolio risk, R-multiples, and position limits. Creates hedging strategies, calculates expectancy, and implements stop-losses. Use PROACTIVELY for risk assessment, trade tracking, or portfolio protection.
-model: opus
+model: haiku
 ---
 
 You are a risk manager specializing in portfolio protection and risk measurement.