Add sessions webpage to ApprovalService with activity log display

[Copilot]

This PR adds a new webpage to the ApprovalService that displays all agent sessions and their activity logs in a user-friendly format for human overview and analysis.

New Features

API Endpoints

• GET /api/sessions - Lists all sessions with metadata (name, status, timestamps, activity count)
• GET /api/sessions/{id} - Gets detailed session information with complete activity log

Web Interface

• New Sessions Dashboard (/sessions.html) - Interactive webpage showing all sessions
• Navigation - Added navigation links between Tool Approvals and Sessions pages
• Session Details - Click any session to expand and view its complete activity log
• Activity Log Presentation - User-friendly display of activities with:
  • Color-coded status indicators (green for success, red for errors)
  • Formatted timestamps and durations
  • Expandable JSON data sections
  • Activity type badges and descriptions

Implementation Details

• Added AgentAlpha project reference to ApprovalService for session data access
• Created SessionsController that integrates with existing ISessionManager
• Reused existing session management infrastructure without modification
• Added dependency injection configuration for session management services
• Responsive web design matching existing ApprovalService styling

Screenshots

The sessions page displays:

• Session list with metadata (name, ID, status, timestamps, activity count)
• Expandable session details showing chronological activity logs
• Formatted activity data with syntax highlighting for JSON
• Error activities highlighted in red for easy identification
• Auto-refresh functionality (every 30 seconds)

Testing

• Verified API endpoints return correct session data
• Tested web interface with sample session data
• Confirmed navigation between approval and sessions pages works
• Validated build process and dependency integration

Fixes #81.

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