fix(editor): keep fullscreen controls above bottom pane tabs

[bajrangCoder]

Fixes: #2766

[greptile-apps]

Greptile Summary

The PR keeps fullscreen navigation controls and their menus at the top when open-file tabs are positioned at the bottom.

• Removes the special bottom anchoring for the main and file menus.
• Removes fullscreen CSS that moved the header and sidebar control above bottom tabs and footer rows.

Confidence Score: 5/5

The PR appears safe to merge, with the menu anchors and fullscreen controls remaining consistently positioned at the top.

The removed special case previously moved both controls and menus to the bottom; the remaining styles and menu options now keep those related elements together at the top without affecting bottom tab or footer placement.

Important Files Changed

Filename	Overview
src/main.js	Makes both header menus consistently top-anchored, matching their togglers’ resulting fullscreen position.
src/styles/page.scss	Removes bottom-position overrides so fullscreen controls use the existing top-positioned layout.

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