chore: update copyright to 2026 and fix favicon 404 warnings

- Updated copyright in mkdocs.yml from 2022-2025 to 2022-2026
- Added favicon.ico (generated from logo) to docs/static/
- Added apple-touch-icon.png (generated from logo) to docs/static/
- Added custom main.html override with extrahead block for proper
  apple-touch-icon and favicon link tags

Author: shenxianpeng

docs/overrides/main.html

@@ -0,0 +1,6 @@
+{% extends "base.html" %}
+
+{% block extrahead %}
+  <link rel="apple-touch-icon" sizes="180x180" href="{{ base_url }}/static/apple-touch-icon.png">
+  <link rel="icon" type="image/x-icon" href="{{ base_url }}/static/favicon.ico">
+{% endblock %}

docs/static/apple-touch-icon.png

@@ -3,7 +3,7 @@ site_description: "Clean commits. Clear standards."
 site_url: "https://commit-check.github.io/"
 repo_url: https://github.com/commit-check
 repo_name: "commit-check"
-copyright: "© Copyright 2022 - 2025, shenxianpeng."
+copyright: "© Copyright 2022 - 2026, shenxianpeng."
 
 nav:
   - Home: index.md