feat(plugins): install and update Git sources (#3920)

Make every trusted Git repository directly distributable without introducing a registry or package manager. Managed checkouts retain their resolved commit, track branches explicitly, and stage validation before activation so failed updates restore the running version.

packages/cli/src/cli-surface.test.ts

@@ -77,6 +77,8 @@ describe("canonical CLI surface", () => {
       "ls",
       "logs",
       "install",
+      "status",
+      "update",
       "reload",
       "enable",
       "disable",