Bring our own eye tracker into the gaze folder, run by the gaze service

frame-eyes, a separate project until now, becomes gaze/tracker:
- ft-eyegrab (was fe-bufprobe) copies the eye-camera frames, read-only, out of
  SteamVR's eyetracking process. It runs as the system service
  frametop-eyegrab.service, which gaze/tracker/install.sh installs to
  /etc/frametop with sudo. It keeps only CAP_SYS_PTRACE, CAP_DAC_READ_SEARCH, and
  CAP_CHOWN, and copies frames only while /dev/shm/frametop-eyes-want is fresh,
  holding none of the tracker's buffers otherwise.
- ft-eyes (was fe-trackd) runs under ft-gazed in the dev container, with
  build/venv's pinned numpy and OpenCV: while Eye tracker is Own tracker, or on
  the probe's lease ("eyes SECONDS"). No sudo password or fe-live script at
  run time any more.
- lab/ holds the research tools (ft-eyes-score, -e2e, -record, -replay,
  -session) and findings.md. Recordings live outside the repo, in
  ~/.local/share/frametop/eyes/captures; .gitignore catches stray frame dumps.

Its socket is now @ft_eyes, its output /dev/shm/frametop-eyes-gaze, and its state
~/.local/state/frametop/gaze/eyes. On practice1 -> practice2 the whole live path
(ft-eyes-e2e) gives 1.30 deg median and 3.18 for the worst tenth, as before the
move (1.30, 3.21).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

input-settings/ft_input_settings.py

@@ -85,7 +85,7 @@ GAZE_SETTINGS = [
     ("POINTER_GAZE_SHOW", "Dot shows after moving", 1.0, 0.0, 5.0, 0.1, "s"),
 ]
 # The gaze service's settings (gaze/ft-gazed): whose eye tracking, and the eye bias.
-GAZE_TRACKERS = {"steam": "SteamVR's eye tracker", "own": "our own eye tracker (frame-eyes)"}
+GAZE_TRACKERS = {"steam": "SteamVR's eye tracker", "own": "our own eye tracker"}
 GAZE_EYES = {"auto": "auto", "left": "left eye", "right": "right eye"}
 # Pointer settings: key, label, default, min, max, step, unit.
 POINTER_SETTINGS = [