feat(skd-decompile): scaffold — Ring 3 fail-fast, sentinel/warnings, query extraction

Layer 1 of the skd-decompile plan: SKILL.md with disable-model-invocation,
ps1 skeleton with XML→JSON pipeline, namespace probe for non-DCS root,
sentinel/warnings accumulator, and DataSetQuery extraction (query only).
Test case minimal-query demonstrates round-trip via skd-compile preRun.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/skills/cases/skd-decompile/_skill.json

@@ -0,0 +1,11 @@
+{
+  "script": "skd-decompile/scripts/skd-decompile",
+  "setup": "none",
+  "args": [
+    { "flag": "-TemplatePath", "from": "workPath", "field": "templatePath" }
+  ],
+  "snapshot": {
+    "root": "workDir",
+    "normalizeUuids": false
+  }
+}

tests/skills/cases/skd-decompile/minimal-query.json

@@ -0,0 +1,19 @@
+{
+  "name": "Минимальный СКД с одним DataSetQuery",
+  "preRun": [
+    {
+      "script": "skd-compile/scripts/skd-compile",
+      "input": {
+        "dataSets": [{
+          "name": "НаборДанных1",
+          "query": "ВЫБРАТЬ Номенклатура.Наименование КАК Наименование ИЗ Справочник.Номенклатура КАК Номенклатура",
+          "fields": ["Наименование"]
+        }]
+      },
+      "args": { "-DefinitionFile": "{inputFile}", "-OutputPath": "Template.xml" },
+      "cwd": "{workDir}"
+    }
+  ],
+  "params": { "templatePath": "Template.xml" },
+  "expect": { "stdoutContains": "НаборДанных1" }
+}