feat(commands): add incremental and parallel feature build commands (#40)

* feat(commands): add incremental-feature-build command

Add comprehensive command for building complex features incrementally,
implementing best practices for long-running agent tasks:

- JSON-based feature tracking with strict modification rules
- Prevents premature completion by requiring all features to pass
- Incremental one-feature-at-a-time workflow
- Git integration for clean commits and recovery protocols
- Progress tracking via dedicated PROGRESS.md file
- Feature expansion guidelines for 50-200+ granular features
- Recovery mechanisms for failed implementations

Based on research into Claude best practices for long-running agents.

* feat(commands): add parallel-feature-build command

Add agent-orchestrated parallel implementation command that extends
the incremental approach with concurrent execution capabilities:

- Dependency graph generation with topological sorting
- Batch identification for parallel-safe feature groups
- Multi-agent orchestration with isolated branches
- Merge coordination with conflict resolution protocols
- Synchronized progress tracking across agents
- Performance reporting with speedup metrics
- Recovery protocols for agent/merge failures

Enables up to Nx speedup for large feature sets with independent
components while maintaining the strict tracking guarantees of
the sequential approach.

* fix(commands): address code review feedback for feature build commands

Improvements to incremental-feature-build.md:
- Replace fragile grep with proper jq queries for JSON validation
- Update feature count guidelines from 50-200 to hierarchical approach
  (10-30 small, 30-60 medium, 60-100 large projects)
- Add epic/module grouping example for better organization
- Update deprecated `git checkout --` to `git restore`
- Add error handling for mkdir failures with troubleshooting guide
- Document $ARGUMENTS placeholder behavior with examples
- Add note explaining status model difference from parallel version

Improvements to parallel-feature-build.md:
- Add circular dependency detection with jq script
- Add polling mechanism with sleep intervals for agent monitoring
- Add explicit feature branch creation step (Phase 2.3)
- Add file locking mechanism for safe concurrent updates
- Fix merge workflow to reference correct feature branch
- Add error handling for directory creation
- Document $ARGUMENTS placeholder behavior

Housekeeping:
- Move development checklist files to .feature-tracking/examples/
  (these are implementation artifacts, not deliverables)

Author: qdhenry