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/coding-style.md

@@ -0,0 +1,46 @@
+---
+paths:
+  - "**/*.pl"
+  - "**/*.pm"
+  - "**/*.t"
+  - "**/*.psgi"
+  - "**/*.cgi"
+---
+# Perl Coding Style
+
+> This file extends [common/coding-style.md](../common/coding-style.md) with Perl specific content.
+
+## Standards
+
+- Always `use v5.36` (enables `strict`, `warnings`, `say`, subroutine signatures)
+- Use subroutine signatures — never unpack `@_` manually
+- Prefer `say` over `print` with explicit newlines
+
+## Immutability
+
+- Use **Moo** with `is => 'ro'` and `Types::Standard` for all attributes
+- Never use blessed hashrefs directly — always use Moo/Moose accessors
+- **OO override note**: Moo `has` attributes with `builder` or `default` are acceptable for computed read-only values
+
+## Formatting
+
+Use **perltidy** with these settings:
+
+```
+-i=4    # 4-space indent
+-l=100  # 100 char line length
+-ce     # cuddled else
+-bar    # opening brace always right
+```
+
+## Linting
+
+Use **perlcritic** at severity 3 with themes: `core`, `pbp`, `security`.
+
+```bash
+perlcritic --severity 3 --theme 'core || pbp || security' lib/
+```
+
+## Reference
+
+See skill: `perl-patterns` for comprehensive modern Perl idioms and best practices.