docs: verify Gitea 1.27.0 compatibility — no mail template changes

Verification results:
- 0 files changed in templates/mail/ or services/mailer/ between v1.26.0 and v1.27.0
- All 110 templates (10 themes × 11 types) render successfully
- No new mail template types, no removed types
- No changes to template functions or data contexts
- No breaking changes for mail templates

Marking v1.0.1 as compatible with Gitea 1.27.0.

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

README.md

@@ -2,7 +2,7 @@
 
 A curated collection of professionally designed, audience-driven email templates for self-hosted [Gitea](https://about.gitea.com) instances.
 
-[![Gitea](https://img.shields.io/badge/Gitea-1.25+%20%7C%201.27.0%20pending-yellow)](COMPATIBILITY.md) <!-- TRACKER:BADGE -->
+[![Gitea](https://img.shields.io/badge/Gitea-1.25+%20%7C%201.27.0%20tested-blue)](COMPATIBILITY.md) <!-- TRACKER:BADGE -->
 
 > **110 template files — 10 visual styles, 11 email types each**