* fix(rich-markdown-editor): show the col-resize cursor on table column borders
prosemirror-tables toggles a `resize-cursor` class on the editor while the pointer is over a
column boundary, but there was no rule to change the cursor — the blue resize handle showed with
no cursor affordance. Add the scoped `col-resize` rule.
* test(rich-markdown-editor): exhaustive markdown paste coverage
Cover every rich construct (headings, marks, lists, task lists, blockquote, code block, image,
thematic break, table), markdown parsed despite an HTML sibling, multi-block order, read-only
rejection, and the defer/verbatim cases for non-markdown input.
* docs(editor): add rich markdown editor page
Document the inline rich markdown editor — formatting, structure, lists, tables, code blocks,
images, the slash menu, and markdown fidelity — with a rendered overview screenshot.
* test(rich-markdown-editor): scope paste tests to what MarkdownPaste actually gates
Inline-only marks (single-asterisk italic, ~~, single-backtick code) are intentionally not detected
by looksLikeMarkdown (single `*` would false-positive on e.g. `*args`); they route through the
Markdown extension's own paste path, not MarkdownPaste. Move them from the rich-render cases to the
defers-to-default cases so the suite tests the handler it names.
