Fix(Forms): Defer MarkdownEditor initialization in collapsed sections and hidden containers

[hamdyelbatal122]

Fixes #20313

Cause

When a MarkdownEditor component is placed inside a collapsed Section or an inactive tab/container, EasyMDE (CodeMirror 5) eagerly attempts to measure character coordinates while the element has no rendered DOM dimensions (visibility: hidden or height: 0). This triggers TypeError: Cannot read properties of null (reading 'top') or TypeError: Cannot read properties of undefined (reading 'map').

Solution

1. Deferred Initialization: Refactored markdownEditorFormComponent to inspect container visibility on init(). If the editor starts inside a hidden/collapsed container, EasyMDE instantiation is deferred until the section is expanded and revealed via ResizeObserver.
2. Init Hook Protection: Added a safe CodeMirror.defineInitHook in markdown-editor.js to prevent unhandled selection measurement errors on zero-rect elements before refresh() runs.

[hamdyelbatal122]

Updated the PR to fix the issue across all collapsed containers (Repeater, Section, Tabs, Accordion, Modal, etc.):

• Dynamic Visibility Checking: Updated isEditorVisible() to walk up parent elements in the DOM tree, inspecting Alpine component collapse states (isCollapsed, isOpen, etc.), [x-cloak], [hidden], and CSS styles instead of relying on specific class names.
• Focus & Click Guards: Added focus and mousedown listeners on CodeMirror to ensure cm.refresh() is triggered synchronously if character metrics are uninitialized prior to selection.
• Post-Expand Reflow Refresh: Scheduled cm.refresh() after expand/reveal transitions complete via double requestAnimationFrame and delayed setTimeout.
• CodeMirror Safety Hook: Wrapped prepareSelection in CodeMirror.defineInitHook to catch any unbuilt line maps safely and trigger a refresh instead of throwing unhandled TypeErrors.

[outatime-io]

I tested the fix in my reproduction repo and can confirm it's working as expected.

https://github.com/outatime-io/filament-collapsed-markdown-editor-reproduction

[danharrin]

#20320 fixes all problems at the root cause