- Network Diagnostics: frameless chrome, log rates, kbps→Mbps, 1-min view
- Network Diagnostics: per-series last-sample hints in left gutter

Pull the empty band above the tabs out by mounting the Timeframe
label + combobox in the QTabWidget's top-right corner widget.  Tabs
sit on the left of the row, the dropdown floats on the right, and the
content cards start straight below.

- Removed the old controlRow + hidden inline title (the chrome title
  bar already carries the dialog title).
- 2 px bottom margin on the corner widget so the combobox doesn't
  butt against the pane border.
- 1 px extra top + bottom padding on tab bar tabs (6 → 7 px) so the
  shared row is tall enough for the combobox without clipping.
- 2 px less top padding on the body layout (10 → 8 px) so the row
  starts closer to the chrome title bar.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>