docs: track Gitea 1.27.2 — verified compatible (annotation versioning)

Gitea 1.27.2 (2026-08-14, security + bugfix release) contains no mail
template changes — verified against the local gitea clone: only
modules/templates/util_render.go (avatar-stack UI fix) differs from
1.27.1, templates/mail and services/mailer are untouched.

Versioning now uses the annotation scheme: release numbers stay on the
project's own scheme and the supported Gitea version is appended in
parentheses — v1.0.1(v1.27.2). Synced everywhere:
- COMPATIBILITY.md: active row v1.0.1(v1.27.2), latest verified 1.27.2,
  Versioning section reworded, 1.27.2 history row added
- README.md / docs/README.zh-CN.md: badge, release line, latest tested,
  versioning bullets
- AGENTS.md: annotation scheme + current release v1.0.1 (tracks 1.27.2)
- gitea-tracker.yml: PR checklist now updates the parenthesized Gitea
  version instead of bumping the release number; new tags only when
  template content changes
- CONTRIBUTING.md: simplified Translations section

The local v1.27.1 tag was removed — it conflicts with the annotation
scheme; releases keep v1.0.x tags.

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

CONTRIBUTING.md

@@ -90,8 +90,6 @@ Any readable commit message in semantic format is welcome. Such as:
 
 ## Translations
 
-Only English and Simplified Chinese are maintained:
-
 - English
 - [简体中文](docs/CONTRIBUTING.zh-CN.md)