feat(monitors): main external display, Samsung ultrawide support

monitors.lua picks the main external (Studio Display, else the Samsung
S34CG50 ultrawide, matched on EDID) and reloads the config when it changes.
Workspaces 1-4, the Wacom mapping, and its active-area aspect follow it.
eDP-1 uses auto-right so it sits beside whichever external is connected.

Also unbinds SUPER+RETURN / SUPER+SHIFT+RETURN (terminal and browser live
on SUPER+CTRL+ALT+J/K) and pins the Fastmail/Beeper scratch workspaces'
comments to eDP-1.

input.lua

@@ -111,18 +111,23 @@ hl.device({ name = "elan9008:00-04f3:43c7", output = "eDP-1" })
 -- flips arbitration to ignore-all. Cost: no tilt in drawing apps. The 90ms
 -- re-enable after the pen leaves proximity is hard-coded in libinput.
 
--- Wacom Intuos BT S: pinned to the Studio Display, matched on EDID description
--- so it survives a different DP connector after re-docking. With that display
--- absent, Hyprland maps across the whole layout, which undocked is just eDP-1.
+-- Wacom Intuos BT S: pinned to the main external display (Studio Display or
+-- Samsung ultrawide, see hypr/monitors.lua, which reloads the config when it
+-- changes). With neither connected it keeps the Studio Display selector,
+-- which matches nothing, so Hyprland maps across the whole layout
+-- (undocked: just eDP-1).
 --
--- The tablet is 152x95mm (16:10) and the display is 16:9, so the active area is
--- cropped to a 152x85.5mm (16:9) band to keep strokes undistorted while still
--- reaching every pixel. The band starts at the top edge, leaving the bottom
--- 9.5mm of the tablet as dead space (the pen there parks at the screen bottom).
+-- The tablet is 152x95mm (16:10). The active area is cropped to a full-width
+-- band with the display's aspect ratio (152x85.5mm for the 16:9 Studio
+-- Display, 152x63.6mm for the 3440x1440 ultrawide) to keep strokes
+-- undistorted while still reaching every pixel. The band starts at the top
+-- edge; below it is dead space (the pen there parks at the screen bottom).
+local monitors = require("hypr.monitors")
+local external, monitor = monitors.external()
 hl.device({
   name = "wacom-intuos-bt-s-pen",
-  output = "desc:Apple Computer Inc StudioDisplay 0x984262A7",
-  active_area_size = { 152, 85.5 },
+  output = external or monitors.externals[1],
+  active_area_size = { 152, monitor and 152 * monitor.height / monitor.width or 85.5 },
   active_area_position = { 0, 0 },
 })