feat(hypr): rework keybindings on SUPER and rename special workspace

Drop the LEADER/HYPR prefixes and bind everything directly on SUPER.
Add media-key, brightness, window/layout and workspace bindings. Rename
the special workspace from 'special' to 'scratchpad' and update the
matching window/workspace rules. Map modmask 73 in the keybindings help
script.

config/hypr/rules.lua

@@ -1,4 +1,4 @@
-hl.workspace_rule({ workspace = "special:special", border_size = 3 })
+hl.workspace_rule({ workspace = "special:scratchpad", border_size = 3 })
 hl.window_rule({
     match = { class = "(blueberry.py|Impala|Wiremix|org.gnome.NautilusPreviewer|com.gabm.satty|Omarchy|About|TUI.float|org.pulseaudio.pavucontrol)" },
     tag =
@@ -9,7 +9,7 @@ hl.window_rule({
     match     = { class = "terminal-pi" },
     float     = true,
     center    = true,
-    workspace = "special:special",
+    workspace = "special:scratchpad",
     size      = { "monitor_w/2", "monitor_h/2" }
 })