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/Wip.vue

@@ -0,0 +1,11 @@
+<template>
+    <div class="a4page-portrait bdr-1 flex flex-col relative overflow-scroll">
+        <RouterLink to="/" class="bdr-2">
+            <img src="/img/memes/epic.jpeg" />
+        </RouterLink>
+        <h1>Click her, she will take you home</h1>
+        <span style="height: 100px"></span>
+        <h1>WIP</h1>
+        <h4>Sorry for taking you here</h4>
+    </div>
+</template>