* fix(app): give Markdown and HTML file tabs back their Preview and Source views
The built-in Markdown and HTML panels own one toolbar again: file size,
line count, save status, vim mode, cursor, and a Preview | Source control
over a body that shows the rendered preview or the editor from the same
loaded content and editor model. Plain text files keep the toolbar on top.
The host no longer renders a panel switcher. Source is the built-in panel
for text files no other built-in claims, so it is never offered beside
Markdown or HTML in the picker, the Open with menu, or Settings > Files.
A line target opens the file's built-in panel in its Source view.
* refactor(app): name the shared text file panel TextFilePanel
Markdown and HTML own a Source view; they are not Source panels. The
composite in file-panels/source/panel.tsx is now TextFilePanel, and
SourcePanel is TextFilePanel without a Preview. Names only.
Mohamed Boudra
76b32544c6