Add complete MIDI search and synthesis pipeline

Backend (MVP):
- Express API with /search and /fetch endpoints
- BitMidi and Dongrays search adapters with scoring heuristics
- CORS proxy with disk caching and validation
- Quality assessment and file size limits

Frontend Integration:
- Switch to @tonejs/midi parser for reliable MIDI parsing
- MIDIService for backend API communication
- MotifEngine updated to try real MIDI, fallback to synthetic
- Enhanced error handling and logging

Development:
- Concurrent frontend/backend npm scripts
- Basic project documentation

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

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

server/src/services/MIDISearchService.ts

@@ -0,0 +1,63 @@
+import type { SearchAdapter, MIDICandidate } from '../types.js';
+import { BitMidiAdapter } from '../adapters/BitMidiAdapter.js';
+import { DongraysAdapter } from '../adapters/DongraysAdapter.js';
+
+export class MIDISearchService {
+  private adapters: SearchAdapter[];
+
+  constructor() {
+    this.adapters = [
+      new BitMidiAdapter(),
+      new DongraysAdapter()
+    ];
+  }
+
+  async search(query: string): Promise<MIDICandidate[]> {
+    const allResults: MIDICandidate[] = [];
+    
+    // Search all adapters in parallel
+    const searchPromises = this.adapters.map(async adapter => {
+      try {
+        const results = await adapter.search(query);
+        console.log(`${adapter.name}: Found ${results.length} results`);
+        return results;
+      } catch (error) {
+        console.error(`${adapter.name} search failed:`, error);
+        return [];
+      }
+    });
+
+    const results = await Promise.all(searchPromises);
+    
+    // Combine and deduplicate results
+    for (const adapterResults of results) {
+      allResults.push(...adapterResults);
+    }
+
+    // Remove duplicates (same MIDI URL)
+    const uniqueResults = this.deduplicateResults(allResults);
+    
+    // Sort by confidence score
+    uniqueResults.sort((a, b) => b.confidence - a.confidence);
+    
+    // Return top 10 results
+    return uniqueResults.slice(0, 10);
+  }
+
+  private deduplicateResults(results: MIDICandidate[]): MIDICandidate[] {
+    const seen = new Set<string>();
+    const unique: MIDICandidate[] = [];
+
+    for (const result of results) {
+      // Create dedup key from MIDI URL or title+source
+      const key = result.midiUrl || `${result.title}_${result.source}`;
+      
+      if (!seen.has(key)) {
+        seen.add(key);
+        unique.push(result);
+      }
+    }
+
+    return unique;
+  }
+}