feat: implement plugin management UI

drizzle/postgres/0068_plugin_pinned_version.sql

@@ -0,0 +1 @@
+ALTER TABLE "plugins" ADD COLUMN "pinned_version" text;

drizzle/postgres/meta/_journal.json

@@ -477,6 +477,13 @@
       "when": 1791209310758,
       "tag": "0067_external_session_ref",
       "breakpoints": true
+    },
+    {
+      "idx": 68,
+      "version": "7",
+      "when": 1791256340388,
+      "tag": "0068_plugin_pinned_version",
+      "breakpoints": true
     }
   ]
 }