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/hooks/useWebSocket.ts

@@ -57,7 +57,7 @@ const MAX_AGENT_LOGS = 500 // Keep last 500 log lines per agent
 export function useProjectWebSocket(projectName: string | null) {
   const [state, setState] = useState<WebSocketState>({
     progress: { passing: 0, in_progress: 0, total: 0, percentage: 0 },
-    agentStatus: 'stopped',
+    agentStatus: 'loading',
     logs: [],
     isConnected: false,
     devServerStatus: 'stopped',
@@ -188,6 +188,7 @@ export function useProjectWebSocket(projectName: string | null) {
                   newAgents[existingAgentIdx] = {
                     agentIndex: message.agentIndex,
                     agentName: message.agentName,
+                    agentType: message.agentType || 'coding',  // Default to coding for backwards compat
                     featureId: message.featureId,
                     featureName: message.featureName,
                     state: message.state,
@@ -202,6 +203,7 @@ export function useProjectWebSocket(projectName: string | null) {
                     {
                       agentIndex: message.agentIndex,
                       agentName: message.agentName,
+                      agentType: message.agentType || 'coding',  // Default to coding for backwards compat
                       featureId: message.featureId,
                       featureName: message.featureName,
                       state: message.state,
@@ -328,9 +330,10 @@ export function useProjectWebSocket(projectName: string | null) {
   // Connect when project changes
   useEffect(() => {
     // Reset state when project changes to clear stale data
+    // Use 'loading' for agentStatus to show loading indicator until WebSocket provides actual status
     setState({
       progress: { passing: 0, in_progress: 0, total: 0, percentage: 0 },
-      agentStatus: 'stopped',
+      agentStatus: 'loading',
       logs: [],
       isConnected: false,
       devServerStatus: 'stopped',