Allow toggling Caps Lock via both Shift keys

Adds shift:both_capslock alongside compose:caps so pressing both Shift
keys together toggles real Caps Lock. Caps Lock alone remains the
Compose key, and single-Shift behavior is unchanged. Provides an escape
hatch when Caps Lock gets stuck on (e.g. after an fcitx5 desync).

Closes #5981

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

config/hypr/input.lua

@@ -7,7 +7,7 @@
 --   input = {
 --     -- Use multiple keyboard layouts and switch between them with Left Alt + Right Alt.
 --     kb_layout = "us,dk,eu",
---     kb_options = "compose:caps,grp:alts_toggle",
+--     kb_options = "compose:caps,shift:both_capslock,grp:alts_toggle",
 --
 --     -- Use a specific keyboard variant if needed (e.g. intl for international keyboards).
 --     kb_variant = "intl",