Sync from docs/wiki @ c621c8c
Sync from docs/wiki @ 4c4f4dc
Sync from docs/wiki @ 980497e
Add Headless Linux Appliance page; sync manual from docs/wiki New page: boot-to-EFIS on a headless x86-64 Linux box (eglfs-vs-PyQt6-wheel, X/xcb, systemd services, nav-data updater). Also picks up pending docs/wiki edits (Home, Running-from-Source, Widgets-Flight-Instruments) and the sidebar. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Bill Mallard <wpballard@gmail.com>