Added Oxibadge, a minimal Tauri + Svelte desktop client

Scaffolds the oxibadge crate/frontend as a new workspace member, stripped
down to a bare hello-world, and
extends the CI pipeline

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

oxibadge/src-tauri/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "oxibadge"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[lib]
+# The `_lib` suffix may seem redundant but it is necessary
+# to make the lib name unique and wouldn't conflict with the bin name.
+# This seems to be only an issue on Windows, see https://github.com/rust-lang/cargo/issues/8519
+name = "oxibadge_lib"
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[build-dependencies]
+tauri-build = { version = "2", features = [] }
+
+[dependencies]
+tauri = { version = "2", features = [] }