logiguard fork v2: patched GPUI on verified 8c74db0 tree

Rebuilt from the exact zed-industries/zed @ 8c74db00c4053d6c0a9037863d7bd048658da4ca
tree (previous orphan was based on a stale/wrong fetch). Same 3-file patch:
  - serial.rs: add SerialKind::KeyboardEnter
  - client.rs: store wl_keyboard.enter serial; add latest_serial_of()
  - window.rs: activate() uses keyboard-enter serial (Mutter focus gate)

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

crates/multi_buffer/Cargo.toml

@@ -0,0 +1,63 @@
+[package]
+name = "multi_buffer"
+version = "0.1.0"
+edition.workspace = true
+publish.workspace = true
+license = "GPL-3.0-or-later"
+
+[lints]
+workspace = true
+
+[lib]
+path = "src/multi_buffer.rs"
+doctest = false
+
+[features]
+test-support = [
+    "buffer_diff/test-support",
+    "gpui/test-support",
+    "language/test-support",
+    "text/test-support",
+    "util/test-support",
+]
+
+[dependencies]
+anyhow.workspace = true
+clock.workspace = true
+collections.workspace = true
+ctor.workspace = true
+futures-lite.workspace = true
+buffer_diff.workspace = true
+gpui.workspace = true
+itertools.workspace = true
+language.workspace = true
+log.workspace = true
+parking_lot.workspace = true
+rand.workspace = true
+rope.workspace = true
+settings.workspace = true
+serde.workspace = true
+smallvec.workspace = true
+sum_tree.workspace = true
+text.workspace = true
+theme.workspace = true
+tree-sitter.workspace = true
+ztracing.workspace = true
+tracing.workspace = true
+util.workspace = true
+unicode-segmentation.workspace = true
+
+[dev-dependencies]
+buffer_diff = { workspace = true, features = ["test-support"] }
+gpui = { workspace = true, features = ["test-support"] }
+indoc.workspace = true
+language = { workspace = true, features = ["test-support"] }
+pretty_assertions.workspace = true
+rand.workspace = true
+settings = { workspace = true, features = ["test-support"] }
+text = { workspace = true, features = ["test-support"] }
+util = { workspace = true, features = ["test-support"] }
+zlog.workspace = true
+
+[package.metadata.cargo-machete]
+ignored = ["tracing"]