test: add comprehensive unit tests for database, parsers, loaders, and MCP tools

- Database layer tests (32 tests):
  - node-repository.ts: 100% coverage
  - template-repository.ts: 80.31% coverage
  - database-adapter.ts: interface compliance tests

- Parser tests (99 tests):
  - node-parser.ts: 93.10% coverage
  - property-extractor.ts: 95.18% coverage
  - simple-parser.ts: 91.26% coverage
  - Fixed parser bugs for version extraction

- Loader tests (22 tests):
  - node-loader.ts: comprehensive mocking tests

- MCP tools tests (85 tests):
  - tools.ts: 100% coverage
  - tools-documentation.ts: 100% coverage
  - docs-mapper.ts: 100% coverage

Total: 943 tests passing across 32 test files
Significant progress from 2.45% to ~30% overall coverage

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

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

tests/unit/database/__mocks__/better-sqlite3.ts

@@ -3,6 +3,7 @@ import { vi } from 'vitest';
 export class MockDatabase {
   private data = new Map<string, any[]>();
   private prepared = new Map<string, any>();
+  public inTransaction = false;
   
   constructor() {
     this.data.set('nodes', []);
@@ -24,7 +25,18 @@ export class MockDatabase {
         items.push(params);
         this.data.set(key, items);
         return { changes: 1, lastInsertRowid: items.length };
-      })
+      }),
+      iterate: vi.fn(function* () {
+        const items = this.data.get(key) || [];
+        for (const item of items) {
+          yield item;
+        }
+      }),
+      pluck: vi.fn(function() { return this; }),
+      expand: vi.fn(function() { return this; }),
+      raw: vi.fn(function() { return this; }),
+      columns: vi.fn(() => []),
+      bind: vi.fn(function() { return this; })
     };
   }
   
@@ -38,6 +50,26 @@ export class MockDatabase {
     return true;
   }
   
+  pragma(key: string, value?: any) {
+    // Mock pragma
+    if (key === 'journal_mode' && value === 'WAL') {
+      return 'wal';
+    }
+    return null;
+  }
+  
+  transaction<T>(fn: () => T): T {
+    this.inTransaction = true;
+    try {
+      const result = fn();
+      this.inTransaction = false;
+      return result;
+    } catch (error) {
+      this.inTransaction = false;
+      throw error;
+    }
+  }
+  
   // Helper to extract table name from SQL
   private extractTableName(sql: string): string {
     const match = sql.match(/FROM\s+(\w+)|INTO\s+(\w+)|UPDATE\s+(\w+)/i);