feat: add Perl language rules and update documentation

Add rules/perl/ with 5 rule files (coding-style, testing, patterns,
  hooks, security) following the same structure as existing languages.
  Update README.md, README.zh-CN.md, and rules/README.md to document
  Perl support including badges, directory trees, install instructions,
  and rule counts.

rules/perl/testing.md

@@ -0,0 +1,54 @@
+---
+paths:
+  - "**/*.pl"
+  - "**/*.pm"
+  - "**/*.t"
+  - "**/*.psgi"
+  - "**/*.cgi"
+---
+# Perl Testing
+
+> This file extends [common/testing.md](../common/testing.md) with Perl specific content.
+
+## Framework
+
+Use **Test2::V0** for new projects (not Test::More):
+
+```perl
+use Test2::V0;
+
+is($result, 42, 'answer is correct');
+
+done_testing;
+```
+
+## Runner
+
+```bash
+prove -l t/              # adds lib/ to @INC
+prove -lr -j8 t/         # recursive, 8 parallel jobs
+```
+
+Always use `-l` to ensure `lib/` is on `@INC`.
+
+## Coverage
+
+Use **Devel::Cover** — target 80%+:
+
+```bash
+cover -test
+```
+
+## Mocking
+
+- **Test::MockModule** — mock methods on existing modules
+- **Test::MockObject** — create test doubles from scratch
+
+## Pitfalls
+
+- Always end test files with `done_testing`
+- Never forget the `-l` flag with `prove`
+
+## Reference
+
+See skill: `perl-testing` for detailed Perl TDD patterns with Test2::V0, prove, and Devel::Cover.