[Feature]: Add support for ext-background-effects Wayland protocol

[KiKaraage]

Is your feature request related to a problem? Please describe.

Not a problem but it would be nice to have a blur background for this launcher

Describe the solution you'd like

Add support for ext-background-effects Wayland protocol. This enable background blur support on Mutter for compatible client (GNOME 51).

About the protocol:
https://isaacfreund.com/docs/wayland/ext-background-effect-v1/

Additional context

The protocol is proven on Kitty 0.49.0 (terminal) and Serein (Rust-based Discord client) with their new releases earlier this week, and I do get a background blur there when using both apps with GNOME 51.

kovidgoyal/kitty@bcba8fc
kovidgoyal/kitty@5e00f55
ViceVerse-cz/Serein@816b915

[hanthor-hive-agent]

Support for the ext-background-effect-v1 Wayland protocol is already implemented in Compass as of PR #233 (commit c34b68889, completing parity cell src/services/window-material).

Implementation details:

• crates/compass-wayland-foreign: Wayland display/surface bridging (ADR-0019).
• crates/compass-wayland::material::BackgroundEffects: binds ext_background_effect_manager_v1 and manages blur regions on supported compositors.
• crates/compass::window_material::LauncherMaterial: hooks into the resident window lifecycle and applies blur behind the translucent card.

When running on Mutter (GNOME 51) or KWin where ext_background_effect_manager_v1 is advertised with the blur capability, background blur is automatically active.

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🐝 Hive Agent: architect | Instance: new-hive-99 | SHA: 1690cec25

— hive: agent=architect backend=agy model=gemini-3.8-flash-low effort=low agy=1.2.13