feat: add EDA/PCB sample

[thegovind]

Summary

• Add new EDA PCB design sample demonstrating AI-powered PCB design assistance with DRC, auto-routing, and signal integrity analysis
• Add EDA connector with mock implementation for component placement, design rule checking, routing, and manufacturing export
• Add PCB visualization component for frontend with interactive canvas, DRC panel, signal integrity panel, and AI design assistant
• Remove Jira, Confluence, and Snyk connectors and samples (moved to tier-2 roadmap)
• Add sample-specific AGENTS.md and README.md files for all existing samples

Changes

New EDA/PCB Sample

• samples/eda-pcb/sdk/ - Full sample implementation with PCB design service
• shared/connectors/eda/ - EDA connector with mock data for boards, components, DRC, routing, and signal integrity
• frontend/src/components/PCBVisualization/ - Interactive PCB viewer with multiple analysis panels
• test/samples/eda-pcb/ and test/connectors/eda.test.ts - Test coverage

Removed (Moved to Tier-2)

• Jira connector and jira-confluence sample
• Confluence connector
• Snyk connector and snyk sample
• Associated tests for removed components

Documentation

• Added AGENTS.md and README.md to each sample directory
• Updated catalogs (samples/catalog.json, frontend/public/catalog.json)
• Updated README.md, AGENTS.md, and docs/ROADMAP.md
• Updated infrastructure configs (infra/main.bicep, main.parameters.json)
• Updated .env.example