- Read-only markdown files mount as Toast UI Viewer, which already
has no edit toolbar / no caret — the absence is itself the cue.
Drop the explicit red banner; keep the disabled-Save tooltip.
- YAML front-matter textarea no longer shows a placeholder example
(title/date/tags). A file without front matter renders as a
genuinely empty pane instead of looking like it has content.
- YAML editor's banner stays — CodeMirror readOnly has no
built-in visual signal beyond the disabled caret.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>