Add hugo-cloak-email theme

- Include hugo-cloak-email in the theme list in config.toml
- Add submodule for hugo-cloak-email theme
- Update .gitmodules to include the new submodule

This change enhances email protection on the website by cloaking email addresses.

config.toml

@@ -1,5 +1,5 @@
 title = "Eric's Personal Page"
-theme = "hugo-coder"
+theme = ["hugo-cloak-email", "hugo-coder"]
 languageCode = "en"
 defaultcontentlanguage = "en"
 paginate = 20