* Add move and copy operations

- AtomOp: add 'move' | 'copy', IAtomOperation: add from? field
- validateAtom: move/copy validation with self-move prevention
- applyAtom: resolveValueAtPath helper, applyMoveOp, applyCopyOp
- invertAtom: move swaps from/path, copy→remove with oldValue
- fromAtom: throws for move/copy (v4 changeset incompatible)
- 47 new tests covering validation, apply, inversion, sequential
  semantics, and edge cases
- Bumps to 5.0.0-alpha.7

* Address review: use parseAtomPath in resolveValueAtPath, fix root move

- resolveValueAtPath now uses parseAtomPath typed segments instead of
  regex on atomic path — correctly handles bracket properties
- Root ($) excluded from self-move subtree check — moving from root
  to a descendant is valid
- Remove unused splitJSONPath import

* Address review: literalKey in resolve, null filter match, coverage

- resolveValueAtPath respects literalKey for bracket-notation filters
- Remove != null guard to allow null filter value matching
- Add value-filter test for codecov coverage
- Update docstring

* Add type guards in resolveValueAtPath, handle undefined in copy

* Add type guard coverage tests, fix codecov patch threshold