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/terminal/mail/repo/issue/default.tmpl

@@ -97,7 +97,7 @@
         <table border="0" cellpadding="0" cellspacing="0" width="100%" style="margin:24px 0 20px; border-collapse:separate;">
           <tr>
             <td align="left">
-              <a href="{{.Link}}" style="display:inline-block; padding:11px 24px; font-size:14px; font-weight:700; color:#0d1117; text-decoration:none; background-color:#00ff41; border:2px solid #00ff41; font-family:'JetBrains Mono','Fira Code','Consolas',monospace; letter-spacing:0.5px;">$ view_on_{{AppName}}</a>
+              <a href="{{.Link}}" style="display:inline-block; padding:11px 24px; font-size:14px; font-weight:700; color:#0d1117; text-decoration:none; background-color:#00ff41; border:2px solid #00ff41; font-family:'JetBrains Mono','Fira Code','Consolas',monospace; letter-spacing:0.5px;">{{.locale.Tr "mail.view_it_on" AppName}}</a>
             </td>
           </tr>
         </table>
@@ -116,7 +116,7 @@
 
       <div style="padding:16px 28px 20px; border-top:1px solid #30363d; background:#0d1117;">
         <p style="margin:0; font-size:12px; color:#484f58;">
-          <span style="color:#8b949e;">#</span> &copy; <a href="{{AppUrl}}" style="color:#58a6ff; text-decoration:none;">{{AppName}}</a>
+          <span style="color:#8b949e;">#</span> &copy; <a href="{{AppUrl}}" style="color:#58a6ff; text-decoration:none;">{{AppName}}</a>{{if .CanReply}}&nbsp;{{.locale.Tr "mail.reply"}}{{end}}
         </p>
         <p style="margin:4px 0 0; font-size:11px; color:#484f58;">
           <span style="color:#8b949e;">#</span> if (!$expecting) { ignore(); }