fix: add database init entrypoint

[Ghraven]

Summary

Add the missing database/init.js entrypoint used by the existing npm run db:init script.

Bug

package.json defines:

"db:init": "node database/init.js"

but database/init.js did not exist, so the command failed before it could initialize the SQLite database.

Before/After

Before:

npm run db:init
# Error: Cannot find module './database/init.js'

After:

npm run db:init
# Database initialized successfully.

The new entrypoint reuses the existing Database class, initializes the schema/settings, closes the connection, and exits non-zero if initialization fails.

Verification

• npm ci
• node -c database/init.js
• npm run db:init