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-TW.md

@@ -74,7 +74,7 @@ cd tools && go run . dev
 ## 相容性
 
 - **Gitea 1.25+** — v1.25 引入的郵件模板目錄結構
-- **最新測試：** Gitea 1.26.4
+- **最新測試：** Gitea 1.26.4<!-- TRACKER:LATEST-TESTED -->
 - 與 Gitea 官方模板 100% 相容 — 詳見 [COMPATIBILITY.md](COMPATIBILITY.md)
 
 ## 授權