Problem

Currently, when a note has no status assigned, the plugin defaults to showing "unknown" status. This creates visual noise and conceptual confusion - a note without status should simply have no status, not an "unknown" status.

Current behavior

• Notes without frontmatter status → ['unknown']
• Notes with empty/invalid status → ['unknown']
• "unknown" appears in status pane, file explorer icons, status bar, etc.

Proposed behavior

• Notes without frontmatter status → [] (empty array)
• Notes with empty/invalid status → []
• UI components handle empty status arrays gracefully
• No "unknown" status concept in the system

Impact areas

• StatusService.getFileStatuses() - return [] instead of ['unknown']
• Status pane - handle empty status arrays
• File explorer icons - skip files with no status (respects existing hideUnknownStatusInExplorer setting)
• Status bar - show "No status" or hide completely when empty
• Status dropdown - show "No status assigned" state

Benefits

• Cleaner, more intuitive UX
• Reduces visual clutter
• Better performance (fewer files to process in status pane)
• More logical: no status = no status, not unknown status

Breaking change?

Potentially yes - users with workflows depending on "unknown" status would need to migrate. Could be mitigated with a setting to preserve legacy behavior during transition period.