File references in chat messages can now use the 'path:start-end'
form (e.g. 'src/foo.ts:120-145'). The reference becomes clickable in
the renderer and, on click, the file opens at the start line. Range
selection is intentionally not done at this layer — the
'path:start-end' form is parsed only so the link resolves to the
correct path; navigation jumps to the start line, matching the
behavior of the existing 'path:line' form.
- Extract the file-reference parser to a dedicated module so it can
be unit-tested without pulling in the markdown renderer's worker
dependencies.
- Add a range branch to 'parseFileReference' and update the
block-code path regex to recognize the new form.
- Switch the colon-form regex to a non-greedy path match so
'path:line:col' is no longer mis-parsed as 'path:line' with the
first numeric suffix dropped into the path.
- Add a unit test covering the new and existing parser forms.