Fixes `Unknown file extension ".css"` error

This release fixes CSS file handling errors and improves the Studio pane layout by truncating long document titles instead of allowing them to overflow.

• Fixes an issue that caused the Error: Unknown file extension ".css" error.
• Long document titles in the Studio pane header now truncate with an ellipsis instead of overflowing into adjacent panes (e.g. when the Comments pane is open).
• fix: show login screen instead of error when session expires