#8002 Windows/Linux: the app menu keeps one slot, and record actions fit beside the window controls

Fixes the three issues the Linux QA pass found on #7964. Report and re-test: https://app.superset.sh/page/linux-desktop-header-chrome-qa-pr-7964-92j3dg

• Controls shifted 44px when the sidebar collapsed (Windows/Linux only). The app menu sat inside the expanded header but after the 52px rail when collapsed. It now owns a rail-width slot at the left in both states, in the expanded header and in the rail's top strip, so the toggle and back/forward start at the same x. The row's top offset is also pinned on every platform, not just macOS.
• Settings had no app menu on Windows/Linux. This predates #7964. It now shows in the same slot.
• The record side header ran its primary action under the window controls. The 372px side column can't hold link/ID/⋯, "Create workspace" and Linux's ~97px of window controls. The side header's actions are now a container, and "Create workspace" / "Go to workspace" drop to an icon (keeping an aria-label) only below 18rem of free space. macOS, with no inset, keeps the full label.

Verified

• Linux: dev build of this branch on Xvfb and openbox, with real screen captures and CDP measurements. Toggle, back and forward sit at identical positions expanded vs collapsed (x 68/102/130, y 23) on Tasks, a task, a workspace and Settings. The app menu is at (26,23) everywhere, and a real click opens the native menu. "Create workspace" ends at x=1319, 24px clear of the controls (which start at x=1343); before, it overlapped them by 13px. 0 console errors.
• macOS (dev app, CDP): all 36 screen × sidebar-state rows unchanged (icons at x 88/122/150, y 23), and both action labels still visible (355px of room).
• Checks: lint, typecheck, i18n (no new strings) and 6,287 renderer tests pass.

Not covered: Windows (no Windows host to test on). The logic is the same as Linux's, except its window controls are wider.

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Summary by cubic

Fixes three issues from the Linux QA pass: the controls shift 44px when the sidebar collapses, Settings lacks an app menu, and record actions run under the window controls.

Bug Fixes

• The app menu now owns a rail-width slot at the left of the header in both expanded and collapsed states, so the toggle and back/forward buttons start at the same x; the top offset is also pinned on every platform, not just macOS.
• Settings now shows the app menu on Windows/Linux in the same slot.
• Record side headers wrap the actions in a container, and "Create workspace"/"Go to workspace" collapse to their icon (keeping an aria-label) only when the header can't fit them; macOS keeps the full labels.

Summary by CodeRabbit

• Accessibility
  • Added accessible labels to the “Go to workspace” and “Create workspace” buttons.
• User Interface
  • When action areas are narrow, the workspace buttons hide their text while keeping the arrow icon visible.
  • Adjusted app menu placement and window-control spacing across desktop platforms, including sidebar layouts and window zoom levels.