Gaze first: precision and drag buttons, key combinations, pointer role

Two new actions for mouse buttons, controller buttons, and key
combinations: gaze_precision (hold: the pointer stops where you look and
the button's device steers it, a controller by where it points at
POINTER_PRECISION_GAIN, the mouse by its moves; release: click there) and
gaze_drag (the same with a real press at once, dragging until the
release). The relay sends "precision|gazedrag <source> 1|0" to the
helper, which runs them through the same holds as pinches and grips.

- Key combinations on any keyboard ("key_bindings" in the rules, e.g.
  Ctrl+Alt+G for gaze on/off): the last key isn't typed.
- POINTER_GAZE_MOUSE: in gaze mode the left button is a precision button
  (the default, as before) or clicks right away (direct).
- In gaze mode a moving controller no longer takes the pointer away.
- POINTER_ROLE (right, left, stylus): the driver takes a "role" command,
  so the pointer can stay off the hand holding the precision controller,
  which would otherwise take the role back. Needs the rebuilt driver.
- Input Settings: the actions on the Controllers and Buttons pages; on the
  Gaze page the mouse choice, the role, the precision sliders, and key
  combinations (captured from any keyboard).

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

session/frametop.conf.example

@@ -32,6 +32,11 @@ POINTER_GAZE_RETAKE=5      # gaze mode: how far (degrees) you look away from the
 POINTER_GAZE_NUDGE_MAX=8   # gaze mode: a mouse nudge up to this far (degrees) before a click is learned as the eye tracker's error
 POINTER_GAZE_HOLD=0.5      # gaze mode: a press held this long (s) without moving becomes a real press (to drag); moved or released sooner, it clicks where you let go
 POINTER_GAZE_SHOW=1        # gaze mode: the dot shows this long (s) after the mouse moves it; also while a press is held, and a pulse per click
+POINTER_GAZE_MOUSE=precision # gaze mode: the left button holds back its press, the mouse steers, the release clicks (precision) | clicks right away (direct)
+POINTER_PRECISION_GAIN=0.5  # gaze precision (a button mapped to gaze_precision): the pointer turns this times the controller's turn
+POINTER_PRECISION_DEADZONE=0.3 # gaze precision: degrees the controller turns before the pointer does (the press's own jolt)
+POINTER_GAZE_DRAG_GAIN=1   # gaze drag (gaze_drag): the pointer turns this times the controller's turn
+POINTER_ROLE=right         # the hand role the pointer takes: right | left | stylus. A controller held in that hand takes it back (clicks stop landing)
 GAZE_TRACKER=steam         # gaze service: steam = SteamVR's eye tracker | own = our own (frame-eyes' fe-trackd, calibrated in the gaze probe with Own tracker)
 GAZE_EYE=auto              # gaze service: eye bias. auto = each eye weighted by how far off it was at your recent nudges | left | right = that eye counts twice
 HANDS_SWAP_SIDES=0         # hand tracking (hands/run.sh install): 1 = the side cameras' names are swapped, which some SteamVR restarts cause (hands/tools/check_sides.py --ring tells)