feat(FN-3722): route plugin store to configured global directory

Merges centralized plugin installation (FN-3722): TaskStore plugin store is now routed to a configured global directory with legacy migration hardening, and CLI plugin commands are aligned accordingly, backed by comprehensive integration and regression tests. Also includes a dashboard fix to return

Fusion-Task-Id: FN-3722

packages/core/src/db.ts

@@ -1635,6 +1635,10 @@ export class Database {
 
     if (version < 24) {
       this.applyMigration(24, () => {
+        // Legacy project-local plugin table (introduced in v24) is retained for
+        // one-shot migration reads by PluginStore.migrateLegacyProjectRows().
+        // Post-FN-3722 all new plugin install writes must go to central
+        // plugin_installs + project_plugin_states tables; writes here are a bug.
         this.db.exec(`
           CREATE TABLE IF NOT EXISTS plugins (
             id TEXT PRIMARY KEY,