feat: language picker with flags, paging and follow mode, translation run in the floating window

Language picker with search and SVG flags, real pagination with locate, one global machine translation run shown next to uploads.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

frontend/public/flags/my.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 513 342"><path fill="#FFF" d="M0 0h513v342H0z"/><g fill="#c00"><path d="M0 0h513v24.4H0zM0 48.9h513v24.4H0zM0 97.7h513v24.4H0zM0 146.6h513V171H0zM0 195.4h513v24.4H0zM0 244.3h513v24.4H0zM0 293.1h513v24.4H0z"/></g><path fill="#006" d="M0 0h256.5v195.4H0z"/><path d="M153.3 42.1C122.6 30.7 88.5 46.3 77.1 77s4.2 64.8 34.9 76.2c13.3 5 28 5 41.4 0-30.7 24.5-75.4 19.6-100-11.1s-19.6-75.4 11.1-100c26-20.7 62.9-20.7 88.8 0zm26.7 75-20.6 23.3 5.4-30.6-31-1.6 27.3-14.9L143 68l28.6 12 8.4-29.9 8.4 29.9L217 68l-18 25.4 27.3 14.9-31 1.6 5.4 30.6-20.7-23.4z" fill="#fc0"/></svg>