Use /api/v1 with token authentication

All server calls go through a shared axios instance (src/api.js) that gets a token
with API_PASSWORD from the runtime config, renews it before it expires and retries
once on 401. Character images are loaded with the token as blobs. Removes the
unused express and cors dependencies and bumps the version to 1.2.0.

Closes #2

package.json

@@ -1,6 +1,6 @@
 {
    "name": "music-randomizer-vue",
-   "version": "1.1.2",
+   "version": "1.2.0",
    "private": true,
    "scripts": {
       "serve": "vue-cli-service serve",
@@ -10,8 +10,6 @@
   "dependencies": {
        "axios": "^1.7.2",
        "core-js": "^3.37.1",
-       "cors": "^2.8.5",
-       "express": "^4.19.2",
        "vue": "^3.4.31",
        "vue-axios": "^3.5.2",
        "vuex": "^4.1.0"