The cut/copy/paste icons were dead placeholders (no handlers);
clipboard actions live in the floating selection menu, so the second
icon row is removed. The bar goes from two rows at 52dp to one row at
32dp, giving the editor 20dp more height.
- filename_test.go now finds the label by type (back icon precedes it)
- menu tracking tests updated for the new editorY (reg.Y = 10+32)
- scroll_cursor e2e simulation updated to match
- On-device verified: back button works, floating menu places above
with room and flips below on the first lines, handles unaffected.
- Add WriteFile method to mock filesystem (non-atomic path, creates files)
- Implement WriteFileAtomic in mock with temp file + rename pattern
using .tmp/ directory, matching real filesystem semantics
- Update WriteFileTask.Execute() to use WriteFileAtomic
- Update FlushAll() to use WriteFileAtomic
- Fix mock to create files on write (matching os.WriteFile behavior)
- Update tests to match new semantics (create-if-not-exists)
