feat: add skill regression test runner with meta-compile pilot

Snapshot-based test runner (tests/skills/runner.mjs) for verifying
skill script output. Zero dependencies, runs on any machine with
Node.js — no 1C platform needed for daily regression.

Pilot: meta-compile with 6 cases (4 positive with snapshots, 2 negative).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/skills/cases/meta-compile/document-basic.json

@@ -0,0 +1,23 @@
+{
+  "name": "Документ с табличной частью",
+  "input": {
+    "type": "Document",
+    "name": "ПриходнаяНакладная",
+    "attributes": [
+      { "name": "Склад", "type": "String", "length": 100 }
+    ],
+    "tabularSections": [
+      {
+        "name": "Товары",
+        "attributes": [
+          { "name": "Номенклатура", "type": "String", "length": 150 },
+          { "name": "Количество", "type": "Number", "length": 15, "precision": 3 },
+          { "name": "Цена", "type": "Number", "length": 15, "precision": 2 }
+        ]
+      }
+    ]
+  },
+  "expect": {
+    "files": ["Documents/ПриходнаяНакладная.xml"]
+  }
+}