v0.2.68

Added

• Heading level filter — ### filter button in outline sidebar to toggle visibility of sub-subsection cards
• Section highlight on hover — hovering a sidebar card highlights the corresponding section in the editor; optimized with highlightSection()/clearHighlight() API to avoid repeated evaluateJavaScript overhead
• Hover tooltip on card titles — instant tooltip showing full section title when text is truncated, using NSFont measurement for truncation detection

Fixed

• #Notes scroll failure in Milkdown — Swift's BlockParser creates separate blocks per list item, but ProseMirror merges consecutive same-type list items into single nodes, causing block ID count mismatch. Added idsForProseMirrorAlignment() to collapse consecutive same-type list block IDs before sending to JS.
• Scroll to zoomed section on exit zoom — saved zoomedSectionId before async zoomOut clears it, then scrolls after zoom-out completes; wired onContentAcknowledged through CodeMirrorEditor
• CodeMirror horizontal overflow — fixed width issues causing horizontal scrollbar in source editor
• Tooltip z-index rendering behind next card — moved tooltip from per-card overlay to ScrollView-level overlay to fix NSViewRepresentable z-order issue where cards drew on top of previous cards' SwiftUI overlays