fix(plugins): enforce minimum host versions for installable plugins (#52094)

* fix(plugins): enforce min host versions

* fix(plugins): tighten min host version validation

* chore(plugins): trim dead min host version code

* fix(plugins): handle malformed min host metadata

* fix(plugins): key manifest cache by host version

extensions/irc/package.json

@@ -10,6 +10,9 @@
     "extensions": [
       "./index.ts"
     ],
+    "install": {
+      "minHostVersion": ">=2026.3.14"
+    },
     "setupEntry": "./setup-entry.ts",
     "channel": {
       "id": "irc",