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/src/components/util/Time.vue

@@ -0,0 +1,38 @@
+<script setup>
+import Header from "@/components/text/Header.vue";
+import { ref } from "vue";
+
+const time = ref("");
+const weekday = ref("");
+const day = ref("");
+const month = ref("");
+
+function updateDateTime() {
+    const date = new Date();
+    day.value = date.getDate();
+    time.value = date.toLocaleTimeString("en-GB", {
+        hour: "2-digit",
+        minute: "2-digit",
+    });
+    weekday.value = date.toLocaleDateString("en-GB", { weekday: "long" });
+    month.value = date.toLocaleDateString("en-GB", { month: "long" });
+}
+
+updateDateTime();
+
+setInterval(updateDateTime, 60000);
+</script>
+
+<template>
+    <div class="flex flex-col">
+        <Header>{{ weekday }} {{ day }}, {{ month }}</Header>
+        <h1>{{ time }}</h1>
+    </div>
+</template>
+
+<style scoped>
+div {
+    text-align: center;
+    padding: 4px;
+}
+</style>