test: schema version is 80 since 0084

#3874 added 0084_share-anyone-with-link.sql, taking the sqlite chain's
target user_version to 80, but CURRENT_SCHEMA_VERSION stayed at 79 —
and the test workflow only runs on PRs, so main broke silently and every
open PR's 'test (base)' job now fails on it.

src/backend/clients/database/SqliteDatabaseClient.test.ts

@@ -27,7 +27,7 @@ import { DatabaseClientFactory } from './index.js';
 import { SqliteDatabaseClient } from './SqliteDatabaseClient.js';
 
 /** Highest schema version the migration table can reach. */
-const CURRENT_SCHEMA_VERSION = 79;
+const CURRENT_SCHEMA_VERSION = 80;
 
 /**
  * These suites migrate real files on disk. Idle they finish in well under a