chore: bump version to 0.9.0

Cargo.lock

@@ -4693,7 +4693,7 @@ dependencies = [
 
 [[package]]
 name = "usage-monitor"
-version = "0.8.1"
+version = "0.9.0"
 dependencies = [
  "auto-launch",
  "dbus",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "usage-monitor"
-version = "0.8.1"
+version = "0.9.0"
 edition = "2021"
 license = "Apache-2.0"
 description = "Floating bubble showing Claude Code and Codex usage"