Top-level `import { Database } from 'bun:sqlite'` caused Node/Electron's
ESM loader to reject the plugin at module-graph resolution time because
the `bun:` protocol is not in Node's allowed scheme list. This prevented
the OpenCode desktop app from loading the plugin at all.
Fix:
- Remove top-level static import of `bun:sqlite`
- Use a lazy importer (`_bunSqliteImporter`) that calls
`import('bun:sqlite').catch(() => null)` at runtime
- If the import returns null (non-Bun environment), log a warning and
return early — no DB override attempted, plugin loads normally
- Expose `__setBunSqliteImporterForTesting` / `__resetBunSqliteImporterForTesting`
test seams to verify the Node/Electron fallback path
Closes#3795
YeonGyu-Kim