Fixed

• Mindmap editor: Tab key now indents only the current line regardless of text selection, preventing the “Tab selects all then indents everything” trap. Shift+Tab likewise unindents the current line only.
• Mindmap toolbar: Indent and Unindent buttons now collapse the selection after operating (no more accidental full-document selection expansion).
• Navigation dirty-state false positive: switching views now clears stale sidenav dirty flags that leaked when a panel was closed via overlay click or view-switching (rather than via the Cancel/Close button). This prevents the beforeunload “unsaved changes” prompt from firing incorrectly after navigating to Settings or any other view.