feat: Add complete JLCPCB API integration with dual-mode support

Implements full JLCPCB parts catalog integration alongside existing local library search,
giving users two complementary approaches for component selection:

1. Local Symbol Libraries (PR #25)
   - Search JLCPCB libraries installed via KiCad PCM
   - Pre-configured symbols with footprints
   - Works offline, no API needed

2. JLCPCB API Integration (NEW)
   - Complete 100k+ parts catalog access
   - Real-time pricing and stock information
   - Basic/Extended library type identification
   - Cost optimization and alternative suggestions
   - Package-to-footprint mapping

New Features:
- download_jlcpcb_database: Download complete parts catalog to local SQLite DB
- search_jlcpcb_parts: Parametric search with pricing, stock, library type filters
- get_jlcpcb_part: Detailed part info with price breaks and footprint suggestions
- get_jlcpcb_database_stats: Database statistics and status
- suggest_jlcpcb_alternatives: Find cheaper/available alternatives

Implementation:
- Python API client (commands/jlcpcb.py) - JLCPCB API authentication and data fetching
- Parts database manager (commands/jlcpcb_parts.py) - SQLite storage and search
- TypeScript MCP tools (tools/jlcpcb-api.ts) - User-facing tool definitions
- Comprehensive documentation (docs/JLCPCB_USAGE_GUIDE.md)

Database Features:
- ~100k parts with descriptions, pricing, stock levels
- Full-text search on descriptions and part numbers
- Parametric filtering (category, package, manufacturer, library type)
- Package-to-footprint mapping for KiCad
- Intelligent alternative suggestions

Setup Requirements:
- JLCPCB_API_KEY and JLCPCB_API_SECRET environment variables
- One-time database download (~5-10 minutes, 42MB)
- requests library (already in requirements.txt)

Benefits:
- Cost optimization (identify Basic parts = free assembly)
- Real-time stock checking
- Complete catalog access
- Works offline after initial download
- Complements local library search

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/server.ts

@@ -20,6 +20,7 @@ import { registerExportTools } from './tools/export.js';
 import { registerSchematicTools } from './tools/schematic.js';
 import { registerLibraryTools } from './tools/library.js';
 import { registerSymbolLibraryTools } from './tools/library-symbol.js';
+import { registerJLCPCBApiTools } from './tools/jlcpcb-api.js';
 import { registerUITools } from './tools/ui.js';
 import { registerRouterTools } from './tools/router.js';
 
@@ -155,6 +156,7 @@ export class KiCADMcpServer {
     registerSchematicTools(this.server, this.callKicadScript.bind(this));
     registerLibraryTools(this.server, this.callKicadScript.bind(this));
     registerSymbolLibraryTools(this.server, this.callKicadScript.bind(this));
+    registerJLCPCBApiTools(this.server, this.callKicadScript.bind(this));
     registerUITools(this.server, this.callKicadScript.bind(this));
 
     // Register all resources