Notes iteration for WordPress 7.2

[adamsilverstein]

Overall Goal

Following on from the work in #66377, #73260 and #76316 for the last three respective releases, this issue serves as the iteration issue for Notes enhancements, tasks, and bug fixes planned for WordPress 7.2.

Progress is tracked via the sub-issues attached to this issue, listed in rough priority order.

Scope for This Release

Priorities

The proposed focus for 7.2 is on three areas:

1. Emoji reactions (Add emoji reactions as a first class comment type #75144) - Add reactions as a first-class comment type, letting collaborators respond to a note with a lightweight reaction instead of a full reply. In progress, carried over from 7.1.
2. Floating notes in the canvas margin (Render floating notes in the canvas margin instead of an invisible sidebar #79970) - Render notes alongside the content they refer to in the canvas margin (rather than an invisible sidebar), bringing the experience closer to familiar document editors. This also lays the groundwork for the minimized "pills" mode (Add a “Minified Notes Mode” for reduced visual footprint (similar to Google Docs' “Minimize comments”) #73417).
3. Suggestion mode (Add Suggestion mode with Notes #73411) - Explore support for proposing edits as suggestions that can be reviewed, accepted, or rejected, building on the Notes infrastructure.

Other enhancements

Discoverability and indicators

• Notes: improve discoverability of which blocks have notes #73414
• Notes need indicator in block and list-view + associated edit option #73956
• Notes are hard to find: consider promoting "Add note" to the block toolbar #78188
• Add support for identifying new notes #75026
• Notes: Color the avatar ring only when a user is active in the document #80479

Showing and hiding notes

• Add a “Minified Notes Mode” for reduced visual footprint (similar to Google Docs' “Minimize comments”) #73417
• Add a "Show/Hide Notes Panel" command #73812
• Add a toolbar control to show and hide notes #79963
• Need to add “Show More” / “Show Less” toggle in Note. #72822

Notes on new surfaces

• Allow Notes to appear on post previews with a custom capability (aka "Reviewer-friendly workflow") #73418
• Show Discussions outside Editor #71622
• Support Notes for the Style Book #73278
• Make Notes available in templates #72918

Workflow and management

• Support Notes on content spanning multiple blocks #73416
• Notes: all comments view show summary of what's been commented on #73273
• Enhanced Notification support for Notes #72184
• Add a way to "lock" notes for a site, or certain posts #72724
• Ensure notes feature scales to many notes #71668
• Notify users when they are @mentioned in a note #80719

Bug fixes

• Note appears as being attached to a deleted block when two users add them at exactly the same moment using real-time collaboration #74751
• Adding a note closes the already open sidebar and doesn't restore it afterwards #75450
• New notes (unnested) are not properly attached to a block when post is not saved #72717
• Block focus when a note is selected can feel too much like spotlight mode #72860
• Drafted notes are lost when focus is removed from block #73473
• Re-selecting a hidden block loses its note position #73565
• Notes Sidebar container lacks independent mouse scrolling, freezing entirely when post content is short #80449
• Undo restores a deleted inline Note's marker markup without restoring the Note #80672