feat(sync): three way (kobo, koreader and bookorbit) progress and annotation sync (#338)

Introduces a custom KOReader plugin to synchronize reading progress, stats, and annotations. Adds backend controllers, services, and database schema updates to ingest plugin data. Updates the frontend to display KOReader annotations alongside built-in reader highlights.

Closes #337

server/src/config/config.ts

@@ -9,6 +9,7 @@ export const appConfig = registerAs('app', () => ({
   githubReleasesToken: process.env.GITHUB_RELEASES_TOKEN?.trim() || undefined,
   oidcAllowLocalIssuers: parseBooleanFlag(process.env.OIDC_ALLOW_LOCAL_ISSUERS, false),
   koboCloudscraperPython: process.env.KOBO_CLOUDSCRAPER_PYTHON?.trim() || undefined,
+  koreaderPluginSourcePath: process.env.KOREADER_PLUGIN_PATH?.trim() || undefined,
 }));
 
 export const dbConfig = registerAs('db', () => ({