refactor(ci): use marker comments instead of regex for tracker workflow

Add TRACKER: HTML comment markers to COMPATIBILITY.md, README.md, and
all 5 translation READMEs. Rewrite gitea-tracker.yml to use grep -n
for precise line-based insertion and sed line-address editing.

Markers introduced:
- TRACKER:QUICK-REF-MAX  — Quick Reference max tested version
- TRACKER:VERSION-INSERT — Version History row insertion point
- TRACKER:LATEST-VERIFIED — latest verified note version
- TRACKER:BADGE — shields.io badge version
- TRACKER:LATEST-TESTED — latest tested version in READMEs

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

docs/README.zh-CN.md

@@ -79,7 +79,7 @@ cd tools && go run . dev
 ## 兼容性
 
 - **Gitea 1.25+** — v1.25 引入的邮件模板目录结构
-- **最新测试：** Gitea 1.26.4
+- **最新测试：** Gitea 1.26.4<!-- TRACKER:LATEST-TESTED -->
 - 与 Gitea 官方模板 100% 兼容 — 详见 [COMPATIBILITY.md](COMPATIBILITY.md)
 
 ## 许可证