New feature: Plain Markdown Viewer and Editor Tp-Note is now a versatile viewer and editor for **any Markdown file**, not just Tp-Note-formatted files with YAML headers. This makes Tp-Note a practical tool for working with standard Markdown documents across your file system. **Key capability:** By default, when you open a plain Markdown file without a YAML front matter header, Tp-Note opens it directly for viewing and editing **without modifying the file**. No automatic header injection, no filename changes—just clean viewing and editing. **Usage:** - **View only:** `tpnote --view myfile.md` - **Edit and view:** `tpnote myfile.md` - **Convert to Tp-Note file:** `tpnote --add-header myfile.md` (prepends YAML header, enables filename synchronization) The `--add-header` flag now defaults to **disabled** (`arg_default.add_header = false`). This means: - Plain Markdown files are opened as-is without automatic header prepending - To convert a plain Markdown file into a full Tp-Note note with YAML metadata, explicitly pass `--add-header` - Existing Tp-Note files (with YAML headers) continue to work unchanged—header synchronization and filename updates happen automatically