Finalize Dexie-to-SQLite migration prep: docs, circular dep removal, SQL helpers, tests

- Removed all vestigial Dexie/USE_DEXIE_DB references from code and docs
- Centralized DB logic in PlatformServiceMixin; resolved logger/databaseUtil circular dependency
- Modularized SQL helpers (`$generateInsertStatement`, `$generateUpdateStatement`) and added unit tests
- Created/updated migration tracking docs and helper script for cross-machine progress
- Confirmed all lint/type checks and tests pass; ready for systematic file migration

src/services/ProfileService.ts

@@ -221,3 +221,4 @@ export function createProfileService(
 ): ProfileService {
   return new ProfileService(axios, partnerApiServer);
 }
+ 

src/services/indexedDBMigrationService.ts

@@ -129,7 +129,7 @@ export async function getDexieExportBlob(): Promise<Blob> {
  * Retrieves all contacts from the Dexie (IndexedDB) database
  *
  * This function connects to the Dexie database and retrieves all contact
- * records. It requires that USE_DEXIE_DB is enabled in the app constants.
+ * records. The migration tools will automatically handle database access through the PlatformServiceMixin.
  *
  * The function handles database opening and error conditions, providing
  * detailed logging for debugging purposes.