feat(mobile): add connection drag-to-reorder

[datlechin]

Summary

• Add drag-to-reorder for connections in the iOS app using native List + EditButton + .onMove pattern
• Sort connections by (sortOrder, name) instead of alphabetical-only, enabling manual ordering
• Support reorder in both flat mode and grouped mode (within group sections)
• Use manual edit mode toggle button for NavigationSplitView compatibility
• Grouped mode uses global sortOrder renumbering to prevent cross-group collisions
• Hide edit button when tag filter is active; reset edit mode on filter/group toggle changes

Test plan

• Flat mode: enter edit mode → drag connections → exit → verify order persists across restart
• Grouped mode: enter edit mode → drag within a group section → verify order persists
• Tag filter active → verify Edit button is hidden
• Toggle "Group by Folder" while in edit mode → verify edit mode resets
• Existing data (all sortOrder 0) → verify connections appear alphabetically (no change)
• Widget still shows connections in custom order after reorder
• iCloud sync: reorder → verify sortOrder syncs to other devices