fix(templates): cross-validate against official Gitea mail templates

- Fix INK theme: replace .ActiveCodeLives with correct field, remove from non-auth contexts (8 files)
- Fix hardcoded button text: use locale key mail.view_it_on in ember, heritage, ink, mono, terminal, terra (30+ files)
- Add missing {{if .CanReply}}mail.reply{{end}} block to all 10 themes default.tmpl
- Add missing mail.release.note locale label to all 10 themes release.tmpl
- Add missing mail.team_invite.text_3 to ink and terra team_invite.tmpl
- Add missing blockquote CSS to aurora, ink, mono, neon, terra default.tmpl

Verified: all 110 templates compile successfully with Go build-preview.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

themes/ember/mail/repo/issue/assigned.tmpl

@@ -39,7 +39,7 @@
         <table border="0" cellpadding="0" cellspacing="0" width="100%" style="margin:28px 0 24px; border-collapse:separate;">
           <tr>
             <td align="center">
-              <a href="{{.Link}}" style="display:inline-block; padding:14px 40px; font-size:16px; font-weight:600; color:#ffffff; text-decoration:none; background:linear-gradient(135deg, #ea580c, #c2410c); border-radius:50px; font-family:system-ui,sans-serif;">View on {{AppName}} &#x2197;&#xfe0f;</a>
+              <a href="{{.Link}}" style="display:inline-block; padding:14px 40px; font-size:16px; font-weight:600; color:#ffffff; text-decoration:none; background:linear-gradient(135deg, #ea580c, #c2410c); border-radius:50px; font-family:system-ui,sans-serif;">{{.locale.Tr "mail.view_it_on" AppName}}</a>
             </td>
           </tr>
         </table>

themes/ember/mail/repo/issue/default.tmpl

@@ -99,7 +99,7 @@
         <table border="0" cellpadding="0" cellspacing="0" width="100%" style="margin:28px 0 24px; border-collapse:separate;">
           <tr>
             <td align="center">
-              <a href="{{.Link}}" style="display:inline-block; padding:14px 40px; font-size:16px; font-weight:600; color:#ffffff; text-decoration:none; background:linear-gradient(135deg, #ea580c, #c2410c); border-radius:50px; font-family:system-ui,sans-serif;">View on {{AppName}} &#x2197;&#xfe0f;</a>
+              <a href="{{.Link}}" style="display:inline-block; padding:14px 40px; font-size:16px; font-weight:600; color:#ffffff; text-decoration:none; background:linear-gradient(135deg, #ea580c, #c2410c); border-radius:50px; font-family:system-ui,sans-serif;">{{.locale.Tr "mail.view_it_on" AppName}}</a>
             </td>
           </tr>
         </table>
@@ -116,7 +116,7 @@
 
       <div style="padding:20px 32px 24px; background:#fff7ed; border-top:1px solid #fed7aa;">
         <p style="margin:0; font-size:14px; color:#92400e;">
-          &copy; <a href="{{AppUrl}}" style="color:#ea580c; text-decoration:none; font-weight:600;">{{AppName}}</a>
+          &copy; <a href="{{AppUrl}}" style="color:#ea580c; text-decoration:none; font-weight:600;">{{AppName}}</a>{{if .CanReply}}&nbsp;{{.locale.Tr "mail.reply"}}{{end}}
         </p>
         <p style="margin:8px 0 0; font-size:13px; color:#a8a29e;">Built with &#x2764;&#xfe0f; by the community, for the community.</p>
       </div>