Droid Chief fix

[droidchief]

Fix raw editor focus lifecycle crash after widget disposal

Problem

• App can crash with: “Null check operator used on a null value” from Quill raw editor focus/keyboard flow during screen transitions.

Cause

• A post-frame focus callback can run after the editor is disposed.
• didUpdateWidget could re-attach focus listeners even in read-only transitions, increasing stale callback risk.

Fix

• Added mounted guards in _handleFocusChanged and its post-frame recursion.
• Updated didUpdateWidget focus-listener logic to only attach when appropriate (non-read-only) and always detach old listener safely.
• Result: prevents stale focus callbacks from accessing disposed editor context.