Extract Vue frontend into separate container and add stp_wasm crate

Move Vue app from nginx/vue/ to top-level vue/ with its own Dockerfile,
update docker-compose configs and nginx proxy to serve from the new
container, and add initial Rust WASM crate (stp_wasm). Also fix .gitignore
to exclude Rust target/ directories.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vue/crates/stp_wasm/src/lib.rs

@@ -0,0 +1,6 @@
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+pub struct BadApplePlayer {
+    is_playing: bool,
+}