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

drizzle/sqlite/0031_smooth_scarlet_witch.sql

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

drizzle/sqlite/meta/_journal.json

@@ -218,6 +218,13 @@
       "when": 1790169397528,
       "tag": "0030_quick_felicia_hardy",
       "breakpoints": true
+    },
+    {
+      "idx": 31,
+      "version": "6",
+      "when": 1790176258239,
+      "tag": "0031_smooth_scarlet_witch",
+      "breakpoints": true
     }
   ]
 }