Fix: Add Windows support for SQLite database access (Issue #23)

Replace CLI-based sqlite3 extraction with better-sqlite3 library:
- Create shared src/db/database.js module for cross-platform SQLite access
- Remove duplicate extractTokenFromDB functions from token-extractor.js and account-manager.js
- Add better-sqlite3 dependency with prebuilt Windows/Mac/Linux binaries
- Improve error handling with specific messages for common issues

Fixes #23

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

package.json

@@ -48,6 +48,7 @@
     "node": ">=18.0.0"
   },
   "dependencies": {
+    "better-sqlite3": "^12.5.0",
     "cors": "^2.8.5",
     "express": "^4.18.2"
   }