Performance Optimization: Advanced Solver Roadmap

Part of #21.

## Overview
The OR-Tools CP-SAT solver can be further optimized for speed and efficiency. This roadmap tracks the implementation of advanced optimizations to reduce search space, provide better starting points, and tighten variable domains.

**Status:** This roadmap blocks the finalization of #27 (GitBook Documentation Migration) as architectural changes here must be documented.

## Sub-Tasks
- [ ] #40 Solver Optimization: Participant Symmetry Breaking
- [ ] #41 Solver Optimization: Solution Hinting (Warm Starts)
- [ ] #42 Solver Optimization: Tighter Objective Bounds
- [ ] #43 Solver Optimization: Hard vs. Soft Grouper Toggle
- [ ] #44 Solver Optimization: Advanced Solver Parameters