Implement MCP Traffic Capture and Protocol Analysis

## Overview
Add capability to capture and analyze MCP protocol traffic for security monitoring and debugging.

## Business Value
Traffic analysis enables detection of attacks, anomalies, and protocol violations in real-time.

## Current State
- Health monitoring exists
- No traffic capture
- No protocol analysis

## Subtasks
- [ ] Design traffic capture architecture
- [ ] Implement traffic interception
- [ ] Add protocol parsing
- [ ] Create traffic storage system
- [ ] Implement traffic analysis
- [ ] Add traffic visualization
- [ ] Create traffic search

## Implementation Steps
1. Create backend/internal/monitoring/traffic_capture.go
2. Implement MCP protocol parser
3. Add traffic storage
4. Create analysis engine
5. Build traffic viewer UI

## Acceptance Criteria
- [ ] MCP traffic is captured
- [ ] Protocol messages are parsed
- [ ] Traffic is stored for analysis
- [ ] Anomalies are detected
- [ ] Traffic can be searched
- [ ] UI displays traffic flows

## Estimated Effort
- Hours: 24-32
- Complexity: High

Start by reading the existing health-monitoring implementation and then inspect backend/internal/monitoring/traffic_capture.go as the proposed entry point. Work through the listed subtasks and acceptance criteria: capture and parse MCP traffic, store and analyze it for anomalies, support search, and display traffic flows in the UI.

Written by the indexing model from the issue text.