fix: audit fixes — power timeout, timing mitigation, release profile, GREETD_SOCK cache (v0.7.1)

- Add 30s timeout with SIGKILL to power actions (adapted from moonset)
- Add 500ms minimum login response time against timing enumeration
- Cache GREETD_SOCK in GreeterState at startup
- Add [profile.release] with LTO, codegen-units=1, strip
- Add compressed="true" to GResource CSS/SVG entries
- Add SYNC comments to duplicated blur/background functions
- Add nix dependency for signal handling in power timeout

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "moongreet"
-version = "0.7.0"
+version = "0.7.1"
 edition = "2024"
 description = "A greetd greeter for Wayland with GTK4 and Layer Shell"
 license = "MIT"
@@ -16,6 +16,7 @@ toml = "0.8"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 graphene-rs = { version = "0.22", package = "graphene-rs" }
+nix = { version = "0.29", features = ["signal"] }
 zeroize = { version = "1", features = ["std"] }
 log = "0.4"
 systemd-journal-logger = "2.2"
@@ -23,5 +24,10 @@ systemd-journal-logger = "2.2"
 [dev-dependencies]
 tempfile = "3"
 
+[profile.release]
+lto = "thin"
+codegen-units = 1
+strip = true
+
 [build-dependencies]
 glib-build-tools = "0.22"