0.1.1

A whole-project audit, then the work it turned up. The headline was that the preprocessing pass could not see inline code, so a regex in backticks aborted the build[^a-z] was read as a reference to a note called a-z. An unresolved marker is prose now, and a mistyped label is caught from the other side instead. with an error naming a note nobody had written.

Also fixed:

• Tildes inside a code span no longer become <del>
• A fence closes only on a matching run, so a longer fence holds a shorter one
• A fenced block indented under a list item stays in its item
• Front-matter slugs and note labels are validated before they reach the output
• Repeating one note reference no longer repeats its id

And the shape of the thing: building a document is separate from writing it, so the layouts are testable, and there is now a fixture site with a committed tree of expected output covering the third of the source that no test reached.