I want to extend the `meld` tool in this code to also be able to grab a section from any markdown doc or JS/TS object and embed its content in the built output using imports

For markdown imports:

- dumb matching: don’t care how many # in the header level in the doc, just select the first one in the targeted document
- select the content up until the next # header 
- skip matching any # inside backtick fences for both startpoints and endpoints
- just error and break the build if a doc or header isn’t found or if multiple matches or some other logical error

## Basic Import from markdown
@import[../docs/setup.md # Installation]

## Import from markdown with Level Adjustment
@import[../docs/api.md # Endpoints] as ###

## Import from markdown with Title Override
@import[../docs/guide.md # Setup] as ### Quick Start

## import function from code
@import[src/meld.ts # myFunction]

## Use braces to export all of x
@import[src/meld.ts # {interface}]
@import[src/meld.ts # {type}]

# Use brackets to import multiple
@import[src/meld.ts # [{interface}, {type}]]
@import[src/meld.ts # [myFunction, otherFunction]]

# Path aliases
- defined in a `meldconfig.json` in project root or in `~/.meldrc` globally

# Import from alias
@import[@docs/setup.md # Installation]