fix(move): restore rollback file contents on failure

[DivyamTalwar]

Summary

• restore original moved-file contents during rollback after a failed write later in the move flow
• restore original moved-directory file contents during rollback after failed external rewrites
• add regression coverage for both file-move and directory-move rollback paths

Root Cause

app.commands.move.move_apply was moving files/directories and then rewriting contents, but it no longer snapshotted the moved target contents before those rewrites. If a later write failed, rollback moved the target back to the source path without restoring the original contents first, which could leave a failed move with mutated source files.

Validation

• make ci
• targeted rollback regression tests in tests/commands/test_transitive_engine.py
• package smoke from make ci