qemu: drive scripted UI scenarios

ui-shot.sh proves touch reaches the UI in one tap. Verifying a UI change needs
a SEQUENCE -- swipe through the app rows, open a submenu, tap a tab, bring up
the keyboard -- and booting per step costs about a minute under TCG, so:

- qmp.py gains a `drive` mode: one connection, one boot, a script of
  tap/swipe/fling/shot/sleep steps in PANEL PIXELS rather than the raw
  0..32767 tablet axis. Swipes interpolate their motion, because LVGL decides
  a gesture from the movement between indev polls and a press-then-release
  with nothing in between is a click, not a scroll.
- ui-drive.sh runs such a script against a booted VM and collects the
  screenshots.

It also FAILS on a UI that died mid-script. warden-ui crashing leaves its last
frame in the framebuffer, so screendumps keep returning a plausible picture of
a program that no longer exists; stage-2 init now announces the exit and its
status on the console, and ui-drive.sh greps for that after the run. This is
what caught the SIGSEGV behind flare-edge#125.

Stage-2 init also mounts devpts. The UI's Terminal page opens a PTY, so
without it that page could only ever report "no PTY available" -- it rendered,
which made a screenshot scenario look fine while the one thing the page does
was untestable.

tests/scripts/nav-stress.txt is the first committed drive script: the
navigation sequence that reproduces flare-edge#125.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T2D2KtdgwbhbF6Mo64eUrn

qemu/README.md

@@ -68,6 +68,7 @@ All take the virt-fragment `<zImage>`; `FLARE_EDGE=<checkout>` where noted.
 | `portal-scenario.sh` | `FLARE_EDGE` | real flared against the desk mock portal: authenticated check-in, desired-state pull, signed tier-1 `.wfw` download; verify/stage/APPLYING as a dry run (no `WARDEN_FW_ALLOW_APPLY`) |
 | `ota-apply.sh` | `FLARE_EDGE` | the FULL apply: the `.wfw`'s bootable rootfs payload is written to rootfs_b (`run.sh --allow-apply` gates it per boot), the AvbABData in `misc` flips, and slot `_b` boots the applied version |
 | `ui-shot.sh` | - | display+touch, headless: QMP-screendumps the 720x720 UI, taps the Metrics tab via `input-send-event`, asserts the frame changed (`qmp.py` is the QMP client) |
+| `ui-drive.sh <script>` | - | the same rig for a SEQUENCE: boots once, runs a `qmp.py drive` script of taps/swipes/screenshots in panel pixels, and FAILS if warden-ui died on the way (stage-2 init announces the exit on the console). `tests/scripts/nav-stress.txt` is the navigation regression: it reproduces the s_row_left overflow that segfaulted the UI on returning to Settings > Apps |
 | `real-image-boot.sh` | matched `rootfs.img` + `oem.img` | an ACTUAL flare-edge build (placed by `mkimage.sh --rootfs-image/--oem-image`) boots its own init chain to getty; binaries predating known fixes reproduce their bugs faithfully, a time machine for field issues |
 | watchdog (`run.sh --watchdog`) | - | arm `/dev/watchdog`, don't pet: the VM resets ~30 s later (verified) |