Float key in the input relay, docking everything, and the plan for profiles

The input relay owns the float key now: float_toggle (Meta+Shift+F unless the
rules have their own key combinations) floats the window under the pointer, or
the active one over the wallpaper, and docks it if it floats. dock_all puts
every floating window back. Both are mappable to mouse and controller buttons,
and work without pointer mode. The KWin script no longer registers a shortcut,
and ft-floatd drops the old one. Key combinations move to Input Settings'
Keyboard page.

docs/floating-windows.md records the decisions from 2026-09-30 (the title bar
button, Launch as Standalone, profiles), and docs/profiles.md plans profiles.

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

float/ft-float

@@ -2,7 +2,10 @@
 """ft-float: talk to ft-floatd (floating windows in the Frametop desktop).
 
   ft-float float [ID|active]   float a window (default: the active one; for it, a toggle)
+  ft-float float pointer       the float key: float the window under the pointer (else the
+                               active one), or put it back if it floats
   ft-float dock [ID|active]    put a floating window back on the desktop
+  ft-float dock all            put every floating window back
   ft-float close ID            close a window
   ft-float list                the spare outputs and what floats on them
 FT_FLOAT_SOCKET names ft-floatd's socket (default frametop_float).