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/mono/mail/repo/collaborator.tmpl

@@ -38,9 +38,9 @@
       </td></tr>
       <!-- button -->
       <tr><td class="resp-pad" style="padding:0 32px 24px;">
-        
+
         <table border="0" cellpadding="0" cellspacing="0"><tr><td style="border:2px solid #000;padding:14px 32px;">
-          <a href="{{.Link}}" class="resp-btn" style="display:inline-block;font-size:14px;font-weight:900;color:#000;text-decoration:none;letter-spacing:-0.3px;">ACTIVATE</a>
+          <a href="{{.Link}}" class="resp-btn" style="display:inline-block;font-size:14px;font-weight:900;color:#000;text-decoration:none;letter-spacing:-0.3px;">{{.locale.Tr "mail.view_it_on" AppName}}</a>
         </td></tr></table>
         <table width="100%" cellpadding="0" cellspacing="0" border="0" style="margin:24px 0 0;"><tr><td style="padding:12px 16px;background:#f5f5f5;border:1px solid #ccc;">
           <p style="margin:0 0 6px;font-size:11px;color:#888;">{{.locale.Tr "mail.link_not_working_do_paste"}}</p>