docs(airbox-q900): add per-platform download tabs with QDL compile steps for Ubuntu 26.04

[tangzz-radxa]

Summary

Add per-platform download tabs to the Fogwise® AIRbox Q900 "Install System to Onboard UFS" tutorial (zh + en).

Changes

In the Download Files section of fogwise/airbox-q900/getting-started/install-system/onboard-ufs.md:

• Added a <Tabs> group with three options:
  • Windows: point users to the Resource Downloads page for boot firmware, system image files, and the QDL tool.
  • Ubuntu 22.04 / 24.04: same guidance as Windows.
  • Ubuntu 26.04: QDL tool compilation steps from the official linux-msm/qdl README (build section only): install dependencies, clone the source, then meson setup build + meson compile -C build. Notes that build/qdl is the resulting executable.

Background

• On newer Ubuntu versions (26.04), the prebuilt QDL Linux binary may not be available/suitable, so users need to compile QDL from source. The tabs make the download instructions match each platform's workflow.

Scope

• Docs only, 2 files (zh + en), single product scope (fogwise/airbox-q900).