Implement Automated MCP Server Discovery

## Overview
Implement automated discovery of MCP servers on the network with endpoint scanning and auto-registration.

## Business Value
Automated discovery reduces manual configuration effort and helps identify all MCP servers in an environment.

## Technology Stack
- Backend: Go, network programming
- Frontend: TypeScript, React, Next.js
- Protocols: MCP protocol, HTTP/HTTPS
- Scheduling: Cron-based job system

## Skill Level Required
- Intermediate to Advanced
- Understanding of network programming
- Knowledge of port scanning and network protocols
- Experience with background job processing

## Learning Opportunities
- Learn network scanning and discovery techniques
- Understand MCP protocol implementation
- Practice building scheduled job systems
- Gain experience with network security considerations
- Learn about building discovery dashboards

## Impact
This feature automates a critical operational task and demonstrates advanced networking and protocol knowledge. Contributors will work on a challenging problem that combines networking, protocol implementation, and UI development.

## Current State
- Basic discovery infrastructure exists in backend/internal/discovery/
- Endpoint scanner exists but needs completion
- No automated scanning scheduled

## Subtasks
- [ ] Complete endpoint scanner implementation
- [ ] Add network range scanning
- [ ] Implement port scanning for MCP servers
- [ ] Add auto-registration of discovered servers
- [ ] Create discovery scheduling system
- [ ] Add discovery results UI
- [ ] Implement discovery filters and exclusions

## Implementation Steps
1. Complete backend/internal/discovery/endpoint_scanner.go
2. Add network scanning capabilities
3. Implement MCP protocol detection
4. Add scheduled discovery jobs
5. Create discovery dashboard in frontend

## Getting Started
1. Review backend/internal/discovery/ directory structure
2. Study MCP protocol specification
3. Review existing server registration code
4. Check frontend dashboard components for UI patterns

## Acceptance Criteria
- [ ] Can scan specified network ranges
- [ ] Detects MCP servers on common ports
- [ ] Auto-registers discovered servers
- [ ] Discovery can be scheduled
- [ ] Discovery results are displayed in UI
- [ ] False positives are minimized

## Estimated Effort
- Hours: 16-20
- Complexity: High