fix: retire rules/zh from the always-loaded default rules install (#2170)

rules/zh shipped ~17KB of Chinese rule text into the auto-loaded rules tree
of every default install (rules-core installs the bare 'rules' path with
defaultInstall: true), with no paths: frontmatter gating. The content had
also drifted behind both rules/common and the maintained translations in
docs/zh-CN/rules/common (e.g. zh/coding-style.md 48 lines vs the 52-line
docs/zh-CN copy), and 'zh' was already dropped from the installer's language
help in favor of the gated docs-zh-cn locale module (--locale zh-CN).

- move rules/zh/code-review.md to docs/zh-CN/rules/common/code-review.md:
  the only file with no counterpart in the maintained locale tree (fills a
  zh-CN parity gap with rules/common/code-review.md)
- delete the remaining 10 rules/zh files, all older duplicates of
  docs/zh-CN/rules/common content
- update trae-install test to assert the rules tree via rules/web instead

Not addressed here: rules/README.md (~5.5KB of installer docs) still ships
into the auto-loaded tree via the bare 'rules' module path; filtering README
files from rule-tree expansion is a separate decision

tests/lib/install-targets.test.js

@@ -206,12 +206,6 @@ function runTests() {
       )),
       'Should not install Cursor README docs as runtime rule files'
     );
-    assert.ok(
-      !plan.operations.some(operation => (
-        normalizedRelativePath(operation.sourceRelativePath) === 'rules/zh/README.md'
-      )),
-      'Should not flatten localized README docs into Cursor rule files'
-    );
   })) passed++; else failed++;
 
   if (test('does not install root AGENTS.md into Cursor nested context', () => {

tests/scripts/trae-install.test.js

@@ -113,11 +113,11 @@ function runTests() {
       assert.ok(manifestLines.includes('skills/skill-comply/pyproject.toml'));
       assert.ok(manifestLines.includes('rules/common/code-review.md'));
       assert.ok(manifestLines.includes('rules/python/coding-style.md'));
-      assert.ok(manifestLines.includes('rules/zh/README.md'));
+      assert.ok(manifestLines.includes('rules/web/performance.md'));
 
       assert.ok(fs.existsSync(path.join(projectRoot, '.trae', 'skills', 'skill-comply', 'pyproject.toml')));
       assert.ok(fs.existsSync(path.join(projectRoot, '.trae', 'rules', 'python', 'coding-style.md')));
-      assert.ok(fs.existsSync(path.join(projectRoot, '.trae', 'rules', 'zh', 'README.md')));
+      assert.ok(fs.existsSync(path.join(projectRoot, '.trae', 'rules', 'web', 'performance.md')));
     } finally {
       cleanup(homeDir);
       cleanup(projectRoot);