Add keyboard workspace jump labels

[colonelpanic8]

Summary

• add an opt-in keyboard jump mode for overview workspaces
• assign labels in spatial order using 1-9, 0, then a-z
• render configurable centered label badges for both grid and linear layouts
• respect the active XKB layout, consume handled key releases, and close directly onto the selected workspace
• document the feature for Lua and legacy Hyprland configuration
• fix render-pass element pointer access for current Hyprland headers

Testing

• meson compile -C /tmp/hyprtasking-build-codex against Hyprland 0.55.0 headers