feat(cli)!: dsh boots profiles; plugin subcommand manages them via pnpm

dsh --profile <name> replaces the fixed entry modes: --config and -p are
removed, --patch adds overlays over the composed profile, a positional task
selects one-shot mode (requires the headless-runner row), and dsh web stays as
the alias for --profile web carrying the Web flag family as patches. dsh
plugin --profile <name> forwards verbatim to pnpm in the profile directory,
initializes on first use, and reconciles the dsh.plugins layer list after
add/remove (patch-less packages warn and stay plain dependencies). Config
dumps and the keyless web e2e scaffold compose the same bundle layers over the
same empty root as the boot.

packages/bundle/web-app/src/index.ts

@@ -135,6 +135,13 @@ export function apply(ctx: Context, config: Config): void {
     }
     const loader = ctx.get('loader')
     if (loader === undefined) printUrl()
-    else void loader.await().then(printUrl)
+    else {
+      void loader.await().then(() => {
+        // The tree can be disposed while settlement was in flight (early
+        // SIGTERM); a URL line for a dead server would only mislead, and
+        // reading the torn-down port would turn a clean shutdown into a crash.
+        if (ctx.get('httpServer') !== undefined) printUrl()
+      })
+    }
   }
 }