feat(chord): v2 slice 7c, plugins component and per-plugin load and reload

Plugin discovery, esbuild builds (optional peer dependency), vm evaluation with
pluginFile and mapStack, dependency installs, a watcher with dirty marks and
rollout across hosts; host.load and host.reload per plugin with the closure rule;
examples 35-39 as folders with real plugin directories.

package-lock.json

@@ -3387,7 +3387,7 @@
 			"version": "0.28.2",
 			"resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.28.2.tgz",
 			"integrity": "sha512-HKVLS8dvII+xoKW9kmqxbRKrnWEXfJJr/FZhhJmiqIB0e053QNYFqOBouTMO/k5sID4MvCiUCvv8b9M4h32wIA==",
-			"dev": true,
+			"devOptional": true,
 			"hasInstallScript": true,
 			"license": "MIT",
 			"bin": {
@@ -5823,6 +5823,14 @@
 			},
 			"engines": {
 				"node": ">=22.19.0"
+			},
+			"peerDependencies": {
+				"esbuild": "0.28.2"
+			},
+			"peerDependenciesMeta": {
+				"esbuild": {
+					"optional": true
+				}
 			}
 		},
 		"packages/codemode": {