feat(devtools): scaffolding (just new-plugin) + just-таргеты

templates/plugin (валидный манифест+locales+README); new-plugin генерит и валидирует;
validate-manifest / plugin-dev-run (каркас, App-Host v3) / sim (плейсхолдер v2). plugins/ — в .gitignore.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Alexander <akotenev2003@gmail.com>

templates/plugin/manifest.yaml

@@ -0,0 +1,11 @@
+plugin:
+  id: dev.example.__NAME__
+  name: "__NAME__"
+  version: 0.1.0
+  shturman_api: "1"
+capabilities:
+  ui_tiles: 1
+extension_points:
+  tiles:
+    - id: main
+      title: "__NAME__"