feat: full desktop passthrough with dynamic cursor hole

Replace static input region with a dynamically updated wl_region that
follows the cursor. The full screen receives pointer events except for a
512px hole around the cursor position, allowing clicks and scrolls to
pass through to the desktop. Cursor avoidance shader updates in sync.

Cargo.lock

@@ -345,6 +345,12 @@ dependencies = [
  "hashbrown 0.16.1",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
+
 [[package]]
 name = "jni-sys"
 version = "0.3.1"
@@ -492,6 +498,16 @@ dependencies = [
  "jni-sys 0.3.1",
 ]
 
+[[package]]
+name = "niri-ipc"
+version = "25.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "12bd9eb4e437f5282ce853cf66837658379cb537b4b6bae687da59246005329a"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "nix"
 version = "0.29.0"
@@ -731,6 +747,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "bytemuck",
+ "niri-ipc",
  "nix",
  "pollster",
  "raw-window-handle",
@@ -807,6 +824,19 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.149"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83fc039473c5595ace860d8c4fafa220ff474b3fc6bfdb4293327f1a37e94d86"
+dependencies = [
+ "itoa",
+ "memchr",
+ "serde",
+ "serde_core",
+ "zmij",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -1366,3 +1396,9 @@ dependencies = [
  "quote",
  "syn",
 ]
+
+[[package]]
+name = "zmij"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8848ee67ecc8aedbaf3e4122217aff892639231befc6a1b58d29fff4c2cabaa"