feat: add dedicated testing agents and enhanced parallel orchestration

Introduce a new testing agent architecture that runs regression tests
independently from coding agents, improving quality assurance in
parallel mode.

Key changes:

Testing Agent System:
- Add testing_prompt.template.md for dedicated testing agent role
- Add feature_mark_failing MCP tool for regression detection
- Add --agent-type flag to select initializer/coding/testing mode
- Remove regression testing from coding prompt (now handled by testing agents)

Parallel Orchestrator Enhancements:
- Add testing agent spawning with configurable ratio (--testing-agent-ratio)
- Add comprehensive debug logging system (DebugLog class)
- Improve database session management to prevent stale reads
- Add engine.dispose() calls to refresh connections after subprocess commits
- Fix f-string linting issues (remove unnecessary f-prefixes)

UI Improvements:
- Add testing agent mascot (Chip) to AgentAvatar
- Enhance AgentCard to display testing agent status
- Add testing agent ratio slider in SettingsModal
- Update WebSocket handling for testing agent updates
- Improve ActivityFeed to show testing agent activity

API & Server Updates:
- Add testing_agent_ratio to settings schema and endpoints
- Update process manager to support testing agent type
- Enhance WebSocket messages for agent_update events

Template Changes:
- Delete coding_prompt_yolo.template.md (consolidated into main prompt)
- Update initializer_prompt.template.md with improved structure
- Streamline coding_prompt.template.md workflow

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ui/src/components/ActivityFeed.tsx

@@ -83,11 +83,30 @@ export function ActivityFeed({ activities, maxItems = 5, showHeader = true }: Ac
 
 function getMascotColor(name: AgentMascot): string {
   const colors: Record<AgentMascot, string> = {
+    // Original 5
     Spark: '#3B82F6',
     Fizz: '#F97316',
     Octo: '#8B5CF6',
     Hoot: '#22C55E',
     Buzz: '#EAB308',
+    // Tech-inspired
+    Pixel: '#EC4899',
+    Byte: '#06B6D4',
+    Nova: '#F43F5E',
+    Chip: '#84CC16',
+    Bolt: '#FBBF24',
+    // Energetic
+    Dash: '#14B8A6',
+    Zap: '#A855F7',
+    Gizmo: '#64748B',
+    Turbo: '#EF4444',
+    Blip: '#10B981',
+    // Playful
+    Neon: '#D946EF',
+    Widget: '#6366F1',
+    Zippy: '#F59E0B',
+    Quirk: '#0EA5E9',
+    Flux: '#7C3AED',
   }
   return colors[name] || '#6B7280'
 }