VR keyboard touch typing, on a controller bridge from the SteamVR dashboard

keyboard.vr.touchTyping (off by default): a key is pressed when a
controller's tip, where SteamVR's laser starts (/pose/tip: the device pose
times the render model's "tip" component), passes through it from the
front; released when pulled back 1 cm, re-armed 5 mm in front. Both hands,
also at once. Keys go through the keyboard's own HandleTouchStart /
HandleTouchEnd, like a laser press (Backspace repeats while held). Options
depth (cm) and haptics.

The geometry lives in a reusable controller bridge (vr-keyboard-controllers,
internal option): a systemui patch reads the keyboard's pose with SteamVR's
SGQueryService (an empty transform of ours in the keyboard's mount) and both
controllers' poses, and streams per hand the tip, the laser's hit on the
keyboard and the trigger (~90 Hz while relevant) through the
vr-keyboard-controllers-relay service to __sfuiControllers in Steam's
SharedJSContext. Tests: flake checks vr-keyboard-controllers and
vr-keyboard-touch.

docs/development.md

@@ -111,6 +111,18 @@ modules/
     dictionary.nix, gen-dict.py  build: dictionary from wordfreq + Hunspell
     check.nix, tests/          test (also built before the patch): text model,
                                corrector, swipe-decoder accuracy, gesture input
+  vr-keyboard-controllers.nix  controller bridge for keyboard features (internal option)
+  vr-keyboard-controllers/
+    bridge-patch.js, unpatch.js  SteamVR: keyboard pose, tips, laser hits, triggers
+    geometry.js                SteamVR (argument of bridge-patch.js): tip/laser -> keyboard
+    hub.js                     Steam (argument of consumer patches): __sfuiControllers
+    relay.mjs                  service vr-keyboard-controllers-relay: frames SteamVR -> Steam
+    check.nix, tests/          test: geometry, hub
+  vr-keyboard-touch.nix        touch typing (keyboard.vr.touchTyping)
+  vr-keyboard-touch/
+    keyboard-patch.js, keyboard-unpatch.js  Steam: presses touched keys
+    tracker.js                 Steam (argument of keyboard-patch.js): contact, hysteresis
+    check.nix, tests/          test (also built before the patch): touch paths
   dashboard-windows.nix, dashboard-windows/     SteamVR: window scale/distance limits
   steam-close-button.nix, steam-close-button/   SteamVR: X on the Steam window
   window-curvature.nix, window-curvature/       SteamVR: curvature wheel
@@ -128,6 +140,8 @@ they are kept even where a file name says more:
 | `launcher-menu` | `launcherMenu` | `launcher-menu-{order,pinned-desktop,launch,grid,show-all}` (Steam) | `steam-ui-patches` |
 | `vr-keyboard` | `keyboard.vr` | `vr-keyboard` (Steam), `vr-keyboard-panel` = `suggestions-panel/` (SteamVR) | `steam-ui-patches`, `vr-keyboard-relay` |
 | `vr-keyboard-extra-keys` | `keyboard.vr.extraKeys` | `steam-keyboard-patch` (Steam) | `steam-keyboard-patch` |
+| `vr-keyboard-touch` | `keyboard.vr.touchTyping` | `vr-keyboard-touch` (Steam) | `steam-ui-patches` |
+| `vr-keyboard-controllers` | (internal, `keyboard.vr.controllers`) | `vr-keyboard-controllers` (SteamVR) | `steam-ui-patches`, `vr-keyboard-controllers-relay` |
 | `dashboard-windows` | `dashboard.windows` | `dashboard-windows` (SteamVR) | `steam-ui-patches` |
 | `steam-close-button` | `dashboard.steamCloseButton` | `steam-close-button` (SteamVR, state) | `steam-ui-patches` |
 | `window-curvature` | `dashboard.windowCurvature` | `window-curvature` (SteamVR) | `steam-ui-patches` |
@@ -137,7 +151,7 @@ they are kept even where a file name says more:
 | `screenshots` | `screenshots` | | `steam-frame-nix-screenshots` (`.service`, `.path`) |
 
 Log of all patches:
-`journalctl --user -u steam-ui-patches -u steam-keyboard-patch -u vr-keyboard-relay`.
+`journalctl --user -u steam-ui-patches -u steam-keyboard-patch -u vr-keyboard-relay -u vr-keyboard-controllers-relay`.
 
 ## Checks