Fix uncategorize undo save error

[Ruby95515]

Summary

Fixes #4425.

This fixes a crash/save error when uncategorizing a duplicated uncle thought and then undoing the change.

Problem

For a tree like:

• a
• b
  • a
    • c

Uncategorizing b/a and then undoing could produce:

Cannot read properties of undefined (reading 'length')

The visible tree operation was mostly correct, but the undo persistence path could enqueue malformed lexeme updates.

Changes

• Prevent uncategorize from merging a child back into the category being deleted when they have the same value.
• Fix undo/redo push queue reconstruction to persist the full lexeme from state instead of forwarding nested JSON patch leaf values.
• Add regression coverage for:
  • uncategorizing same-valued nested thoughts
  • undoing the duplicate-uncle uncategorize case
  • ensuring undo persistence sends complete lexeme updates
  • ensuring the initialized persistence path does not raise the save-error alert

Testing

Passed:

• yarn test src/actions/__tests__/uncategorize.ts src/commands/__tests__/uncategorize.ts src/commands/__tests__/undo-redo.ts
• yarn lint:tsc
• yarn eslint src/redux-enhancers/undoRedoEnhancer.ts src/actions/uncategorize.ts src/actions/__tests__/uncategorize.ts src/commands/__tests__/uncategorize.ts

[github-actions]

Vercel preview: https://em-8oryh1yhu-cybersemics.vercel.app

[raineorshine]

Fix looks good. Just some requests around test architecture.

[BayuAri]

Error is no longer prompted after Undo the Uncategorize with auto merged duplicate parent.

[raineorshine]

Thank you!