feat: finish the fleets plugin, add ctx.hosts and host-commands SDK (B4)

drizzle/postgres/0035_ambitious_klaw.sql

@@ -0,0 +1,2 @@
+-- dropped, see plugin adoption (fleets plugin, migrations/postgres/0001_adopt_fleets.sql)
+SELECT 1;

drizzle/postgres/meta/_journal.json

@@ -246,6 +246,13 @@
       "when": 1790169398038,
       "tag": "0034_free_smiling_tiger",
       "breakpoints": true
+    },
+    {
+      "idx": 35,
+      "version": "7",
+      "when": 1790176258755,
+      "tag": "0035_ambitious_klaw",
+      "breakpoints": true
     }
   ]
 }