refactor: Organize worker into clean route-based HTTP architecture

Major architectural improvements to the worker service:

- Extracted monolithic WorkerService (~1900 lines) into organized route classes
- New HTTP layer with dedicated route handlers:
  - SessionRoutes: Session lifecycle operations
  - DataRoutes: Data retrieval endpoints
  - SearchRoutes: Search/MCP proxy operations
  - SettingsRoutes: Settings and configuration
  - ViewerRoutes: Health, UI, and SSE streaming
- Added comprehensive README documenting worker architecture
- Improved build script to handle worker service compilation
- Added context-generator for hook context operations

This is Phase 1 of worker refactoring - pure code reorganization with zero
functional changes. All existing behavior preserved while improving
maintainability and code organization.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/services/worker/http/routes/ViewerRoutes.ts

@@ -0,0 +1,82 @@
+/**
+ * Viewer Routes
+ *
+ * Handles health check, viewer UI, and SSE stream endpoints.
+ * These are used by the web viewer UI at http://localhost:37777
+ */
+
+import express, { Request, Response } from 'express';
+import path from 'path';
+import { readFileSync } from 'fs';
+import { getPackageRoot } from '../../../../shared/paths.js';
+import { logger } from '../../../../utils/logger.js';
+import { SSEBroadcaster } from '../../SSEBroadcaster.js';
+import { DatabaseManager } from '../../DatabaseManager.js';
+import { SessionManager } from '../../SessionManager.js';
+
+export class ViewerRoutes {
+  constructor(
+    private sseBroadcaster: SSEBroadcaster,
+    private dbManager: DatabaseManager,
+    private sessionManager: SessionManager
+  ) {}
+
+  setupRoutes(app: express.Application): void {
+    app.get('/health', this.handleHealth.bind(this));
+    app.get('/', this.handleViewerUI.bind(this));
+    app.get('/stream', this.handleSSEStream.bind(this));
+  }
+
+  /**
+   * Health check endpoint
+   */
+  private handleHealth(req: Request, res: Response): void {
+    res.json({ status: 'ok', timestamp: Date.now() });
+  }
+
+  /**
+   * Serve viewer UI
+   */
+  private handleViewerUI(req: Request, res: Response): void {
+    try {
+      const packageRoot = getPackageRoot();
+      const viewerPath = path.join(packageRoot, 'plugin', 'ui', 'viewer.html');
+      const html = readFileSync(viewerPath, 'utf-8');
+      res.setHeader('Content-Type', 'text/html');
+      res.send(html);
+    } catch (error) {
+      logger.failure('WORKER', 'Viewer UI error', {}, error as Error);
+      res.status(500).json({ error: 'Failed to load viewer UI' });
+    }
+  }
+
+  /**
+   * SSE stream endpoint
+   */
+  private handleSSEStream(req: Request, res: Response): void {
+    // Setup SSE headers
+    res.setHeader('Content-Type', 'text/event-stream');
+    res.setHeader('Cache-Control', 'no-cache');
+    res.setHeader('Connection', 'keep-alive');
+
+    // Add client to broadcaster
+    this.sseBroadcaster.addClient(res);
+
+    // Send initial_load event with projects list
+    const allProjects = this.dbManager.getSessionStore().getAllProjects();
+    this.sseBroadcaster.broadcast({
+      type: 'initial_load',
+      projects: allProjects,
+      timestamp: Date.now()
+    });
+
+    // Send initial processing status (based on queue depth + active generators)
+    const isProcessing = this.sessionManager.isAnySessionProcessing();
+    const queueDepth = this.sessionManager.getTotalActiveWork(); // Includes queued + actively processing
+    this.sseBroadcaster.broadcast({
+      type: 'processing_status',
+      isProcessing,
+      queueDepth
+    });
+  }
+}