Mobile Markdown files should allow a configurable default view

[brunomartinsmv]

Proposal

Opening a Markdown file from the mobile Files viewer always starts in Source, even though the file supports the rendered Preview view. On a phone, the rendered view is much easier to read.

Current behavior

When opening a .md file on mobile, T3 Code starts in Source. The user can switch to Preview manually, but the choice is not persisted as a default.

The mobile file route recognizes Markdown as preview-capable, but defaultViewMode() selects preview only for browser-preview files, images, and videos. Markdown therefore falls through to source.

Proposed behavior

Ideally, Markdown files should open in Preview by default.

At minimum, T3 Code Mobile should expose a persisted setting that lets the user choose the default mode for Markdown files:

• Preview
• Source

The setting should apply whenever a Markdown file opens without an explicit mode override. The per-file Preview and Source actions should continue to override it for the current file. Source-oriented files such as .py should continue to open in Source.

Why

The rendered Markdown view is considerably easier to read on a phone. Starting in Source adds an extra tap every time and makes the mobile file viewer feel less tailored to Markdown documents.

This proposal follows closed issue #9474, which was redirected here by the maintainers.

This is separate from rendering bugs involving images, SVGs, or raw HTML inside an already-open Markdown preview.