✨(frontend) add floating bar with leftpanel collapse button

[Ovgodd]

Purpose

Add a desktop floating bar and left panel collapse/expand button .

blur.mp4

Proposal

• Add FloatingBar on desktop with a dedicated CollapsePanel button.
• Connect the collapse button to the left panel store to toggle panel open/close.
• When panel is collapsed, display document title in the button (with emoji when available).
• Keep floating bar disabled on mobile for now (temporary choice to avoid overlap/layout regressions).
• Update E2E tests.
• Ensure left-panel filters do not collapse panel on desktop (close only on mobile).

[github-actions]

Size Change: +1.34 kB (+0.03%)

Total Size: 4.2 MB

Filename	Size	Change
apps/impress/out/_next/static/96c0107a/_buildManifest.js	0 B	-831 B (removed)	🏆
apps/impress/out/_next/static/c6d08920/_buildManifest.js	832 B	+832 B (new file)	🆕
apps/impress/out/_next/static/chunks/8495.js	66.3 kB	+1.3 kB (+2.01%)

_{compressed-size-action}

[github-actions]

Size Change: +2.71 kB (+0.06%)

Total Size: 4.21 MB

Filename	Size	Change
apps/impress/out/_next/static/4c23112d/_buildManifest.js	0 B	-896 B (removed)	🏆
apps/impress/out/_next/static/chunks/8495.js	66.7 kB	+1.48 kB (+2.27%)
apps/impress/out/_next/static/f31863d7/_buildManifest.js	893 B	+893 B (new file)	🆕

_{compressed-size-action}