fix(subsystem-edit): write stub XML on add-child operation

Do-AddChild / do_add_child added `<Subsystem>Name</Subsystem>` to the
parent's `<ChildObjects>`, but never wrote the corresponding
`Subsystems/{Parent}/Subsystems/{Name}.xml` file. Same silent-drop
pattern that bit subsystem-compile (aa93031): platform used to swallow
the missing-file reference, `-StrictLog` now surfaces it as "Файл
объекта не существует" and fails add-child on load.

Both ports now mirror the subsystem-compile fix:
- Write-ChildSubsystemStub / write_child_subsystem_stub helpers
  duplicated from subsystem-compile (per memory rule "skills are
  autonomous, duplication acceptable")
- format_version read from loaded XmlDoc root (no need to walk up
  to Configuration.xml — we already have the parent XML in memory)
- Stub creation guarded by Test-Path / os.path.exists so a pre-existing
  real child file is never clobbered

Bumped subsystem-edit.ps1 v1.1→v1.2 and subsystem-edit.py v1.1→v1.2.

Verification:
- verify-snapshots --skill subsystem-edit: 3/4 → 4/4
- runner --filter subsystem-edit (PS1): 4/4
- runner --filter subsystem-edit --runtime python: 4/4 (dual-port drift clean)

With this landed P1 from debug/snapshot-verify/NEXT-STEPS.md is fully
closed: subsystem-compile 7/7, subsystem-edit 4/4, interface-edit 4/4,
role-compile 8/8, meta-compile 30/30.

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

.claude/skills/subsystem-edit/scripts/subsystem-edit.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# subsystem-edit v1.1 — Edit existing 1C subsystem XML
+# subsystem-edit v1.2 — Edit existing 1C subsystem XML
 # Source: https://github.com/Nikolay-Shirokov/cc-1c-skills
 
 import argparse
@@ -7,8 +7,64 @@ import json
 import os
 import subprocess
 import sys
+import uuid
 from lxml import etree
 
+
+def new_uuid():
+    return str(uuid.uuid4())
+
+
+def esc_xml(s):
+    return s.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;').replace('"', '&quot;')
+
+
+def write_utf8_bom(path, content):
+    with open(path, 'w', encoding='utf-8-sig', newline='') as f:
+        f.write(content)
+
+
+def write_child_subsystem_stub(child_path, child_name, format_version):
+    child_uuid = new_uuid()
+    lines = []
+    lines.append('<?xml version="1.0" encoding="UTF-8"?>')
+    lines.append(
+        '<MetaDataObject xmlns="http://v8.1c.ru/8.3/MDClasses" '
+        'xmlns:app="http://v8.1c.ru/8.2/managed-application/core" '
+        'xmlns:cfg="http://v8.1c.ru/8.1/data/enterprise/current-config" '
+        'xmlns:cmi="http://v8.1c.ru/8.2/managed-application/cmi" '
+        'xmlns:ent="http://v8.1c.ru/8.1/data/enterprise" '
+        'xmlns:lf="http://v8.1c.ru/8.2/managed-application/logform" '
+        'xmlns:style="http://v8.1c.ru/8.1/data/ui/style" '
+        'xmlns:sys="http://v8.1c.ru/8.1/data/ui/fonts/system" '
+        'xmlns:v8="http://v8.1c.ru/8.1/data/core" '
+        'xmlns:v8ui="http://v8.1c.ru/8.1/data/ui" '
+        'xmlns:web="http://v8.1c.ru/8.1/data/ui/colors/web" '
+        'xmlns:win="http://v8.1c.ru/8.1/data/ui/colors/windows" '
+        'xmlns:xen="http://v8.1c.ru/8.3/xcf/enums" '
+        'xmlns:xpr="http://v8.1c.ru/8.3/xcf/predef" '
+        'xmlns:xr="http://v8.1c.ru/8.3/xcf/readable" '
+        'xmlns:xs="http://www.w3.org/2001/XMLSchema" '
+        'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
+        f'version="{format_version}">'
+    )
+    lines.append(f'\t<Subsystem uuid="{child_uuid}">')
+    lines.append('\t\t<Properties>')
+    lines.append(f'\t\t\t<Name>{esc_xml(child_name)}</Name>')
+    lines.append('\t\t\t<Synonym/>')
+    lines.append('\t\t\t<Comment/>')
+    lines.append('\t\t\t<IncludeHelpInContents>true</IncludeHelpInContents>')
+    lines.append('\t\t\t<IncludeInCommandInterface>true</IncludeInCommandInterface>')
+    lines.append('\t\t\t<UseOneCommand>false</UseOneCommand>')
+    lines.append('\t\t\t<Explanation/>')
+    lines.append('\t\t\t<Picture/>')
+    lines.append('\t\t\t<Content/>')
+    lines.append('\t\t</Properties>')
+    lines.append('\t\t<ChildObjects/>')
+    lines.append('\t</Subsystem>')
+    lines.append('</MetaDataObject>')
+    write_utf8_bom(child_path, '\n'.join(lines) + '\n')
+
 MD_NS = "http://v8.1c.ru/8.3/MDClasses"
 XR_NS = "http://v8.1c.ru/8.3/xcf/readable"
 XSI_NS = "http://www.w3.org/2001/XMLSchema-instance"
@@ -264,6 +320,7 @@ def main():
     xml_parser = etree.XMLParser(remove_blank_text=False)
     tree = etree.parse(resolved_path, xml_parser)
     xml_root = tree.getroot()
+    format_version = xml_root.get("version") or "2.17"
 
     add_count = 0
     remove_count = 0
@@ -381,6 +438,18 @@ def main():
         add_count += 1
         info(f"Added child subsystem: {child_name}")
 
+        # Write stub XML for the new child if it doesn't exist yet
+        parent_dir = os.path.dirname(resolved_path)
+        parent_base_name = os.path.splitext(os.path.basename(resolved_path))[0]
+        child_subs_dir = os.path.join(parent_dir, parent_base_name, 'Subsystems')
+        if not os.path.exists(child_subs_dir):
+            os.makedirs(child_subs_dir, exist_ok=True)
+            info(f"Created directory: {child_subs_dir}")
+        child_xml = os.path.join(child_subs_dir, f'{child_name}.xml')
+        if not os.path.exists(child_xml):
+            write_child_subsystem_stub(child_xml, child_name, format_version)
+            info(f"Created stub: {child_xml}")
+
     def do_remove_child(child_name):
         nonlocal remove_count
         if child_objs_el is None: