Improved Markdown rendering

### Feature summary

Better Markdown rendering

### What problem are you trying to solve?

I've been using Obsidian for a long time to manage my knowledge bases and view markdown files. The new app is great and I spend more and more time there for knowledge management. The only things that keeps me from migrating completely is the markdown rendered. A few things

- The frontmatter is not nicely rendered as a list
- Callout syntax is not supported (which really makes files more readable)
- Wikilinks to other files should lead me there.

### Proposed solution

_No response_

### Workflow impact

_No response_

### Installation context

_No response_

### Additional context

_No response_

Start by locating the app's Markdown rendering entry point and any existing rendering tests. Review how frontmatter, callouts, and wikilinks are currently handled; done means each is rendered appropriately, wikilinks navigate to their target files, and the relevant tests pass.

Written by the indexing model from the issue text.