T21a: Documents, editing

- markdown read with pulldown-cmark: marks for live styling, blocks, links, words
- forms::Highlight gains weight, slant and strike; measure and paint share runs
- Inter Italic embedded, so emphasis reads slanted
- forms::mention's popup and keys become Suggestions, shared with the editors
- RichTextEditor with FixedFormatToolbar, the floating toolbar, LinkEditor,
  @ and : suggestions, WordCount and ReadingTime
- MarkdownEditor: visual (a pressed block opens as source), source, split
- BlockEditor: prose, lists, to-dos, quotes, callouts, toggles, code, math,
  diagrams the app draws, dividers, tables that grow and merge, pictures to
  resize and align, cards for video and pages, columns, synced text; slash menu,
  markdown shortcuts, handles that drag and open a menu, one undo for all
- TodoItem and Checklist
- icons: heading-1..3, workflow, merge
- gallery: the Documents page with scripted states

tasks/ch21-30.md

@@ -2,26 +2,26 @@
 
 ## T21a Documents · Editing — `src/documents`
 
-- [ ] RichTextEditor
-- [ ] MarkdownEditor — WYSIWYG, source, split
-- [ ] BlockEditor
-- [ ] Block types — paragraph, heading, list, todo, quote, code, divider, table, image, video, embed, math, callout, toggle, columns, synced
-- [ ] BlockHandle
-- [ ] SlashMenu
-- [ ] FloatingFormatToolbar → `overlays::FloatingToolbar`
-- [ ] FixedFormatToolbar
-- [ ] LinkEditor
-- [ ] MentionMenu
-- [ ] EmojiAutocomplete
-- [ ] TableEditor
-- [ ] ImageEditorBlock
-- [ ] MathEditor / LatexBlock
-- [ ] MermaidBlock / DiagramBlock — host renders the SVG
-- [ ] CodeBlockEditor
-- [ ] TodoItem / Checklist
-- [ ] PlaceholderText
-- [ ] WordCount / CharacterCount
-- [ ] ReadingTime
+- [x] RichTextEditor
+- [x] MarkdownEditor — visual, source, split
+- [x] BlockEditor
+- [x] Block types — paragraph, heading, list, todo, quote, code, divider, table, image, video, embed, math, callout, toggle, columns, synced; video and embed open as cards the app plays or shows
+- [x] BlockHandle → the block editor's handle, a `menus::OverflowMenu` that drags its block
+- [x] SlashMenu → `/` in `BlockEditor`
+- [x] FloatingFormatToolbar → `overlays::FloatingToolbar`
+- [x] FixedFormatToolbar
+- [x] LinkEditor
+- [x] MentionMenu → `@` in `RichTextEditor` and `BlockEditor`; `forms::MentionInput` in a field
+- [x] EmojiAutocomplete → a colon and two letters in `RichTextEditor` and `BlockEditor`
+- [x] TableEditor → the block editor's table: rows and columns added and removed, cells merged across
+- [x] ImageEditorBlock → the block editor's picture: resized by its edges, aligned, captioned
+- [x] MathEditor / LatexBlock → the block editor's math block over `typography::Latex`
+- [x] MermaidBlock / DiagramBlock — host renders the SVG → `BlockEditor::diagrams`
+- [x] CodeBlockEditor → the block editor's code block
+- [x] TodoItem / Checklist
+- [x] PlaceholderText → each kind's hint in `BlockEditor`
+- [x] WordCount / CharacterCount → `WordCount`, with `limit` for characters
+- [x] ReadingTime
 
 ## T21b Documents · Reading