Put Folder Sync and Merge path footers on PathMetaFooter

[baseGame]

Summary

• Replace Folder Sync custom selection footer labels with shared PathMetaFooter + pathFileStamp stamps (L/R).
• Replace Folder Merge “Editing disabled” footers with PathMetaFooter stamps (L/Base/R/Output).
• Undo Sync densify crush on path footers (8px → 20px / 11px); keep selection/free-space on the status strip.

Test plan

• Vitest Folder Sync/Merge views + syncMergeChromeDensity, pathStatusDensity, folderChromeDensity, full src/styles/
• Pre-commit quality (prettier, eslint, stylelint, vue-tsc, rust fmt/clippy)
• Spot-check vs docs/assets/.../folder-sync.png, folder-merge.png, folder-compare.png

Remaining divergences

• Folder Compare path footers still use selection-oriented custom labels (not yet full PathMetaFooter stamps).
• Directory stamps show size/mtime only (no encoding/EOL chips — expected for folders).
• Lucide chevrons on format chips when present; Options / Tol panels out of scope.