Fix i18n for form placeholders and make snowflake emoji clickable

- Add data-i18n-placeholder support to i18n.js for dynamic placeholder translation
- Update form inputs with proper i18n attributes for placeholders and labels
- Make snowflake emoji (❄️) clickable on all pages to return to homepage
- Remove snowflake from translation strings since it's now a separate element
- Add i18n support to README features list

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

public/privacy.html

@@ -41,7 +41,7 @@
         <div class="privacy-header">
             <div class="privacy-header__title-wrapper">
                 <div class="privacy-header__title-content">
-                    <h1>❄️ Privacy Policy</h1>
+                    <h1><a href="/" style="text-decoration: none; color: inherit;">❄️</a> Privacy Policy</h1>
                     <p>Great Lakes Ice Report</p>
                 </div>
                 <button id="theme-toggle" class="privacy-header__theme-toggle" title="Toggle theme mode">