feat(astrolabe): upgrade to Vue 3 and @nextcloud/vue 9

- Merge renovate/major-vue-monorepo: Vue 2.7.16 → 3.5.26
- Merge renovate/nextcloud-vue-9.x: @nextcloud/vue 8.29.2 → 9.3.1
- Update component imports to new @nextcloud/vue v9 paths
- Replace .sync modifiers with v-model:prop (Vue 3 syntax)
- Replace beforeDestroy with beforeUnmount lifecycle hook
- Remove Vue.() usage (automatic reactivity in Vue 3)
- Update main.js to use createApp() instead of Vue.extend()
- Add @vitejs/plugin-vue and configure Vite for Vue 3
- All builds passing, ready for admin UX improvements

third_party/astrolabe/package-lock.json

@@ -24,6 +24,7 @@
         "@nextcloud/eslint-config": "8.4.2",
         "@nextcloud/stylelint-config": "3.1.1",
         "@nextcloud/vite-config": "1.7.2",
+        "@vitejs/plugin-vue": "^6.0.3",
         "terser": "5.44.1",
         "vite": "7.2.7"
       },
@@ -2249,6 +2250,13 @@
         "url": "https://opencollective.com/parcel"
       }
     },
+    "node_modules/@rolldown/pluginutils": {
+      "version": "1.0.0-beta.53",
+      "resolved": "https://registry.npmjs.org/@rolldown/pluginutils/-/pluginutils-1.0.0-beta.53.tgz",
+      "integrity": "sha512-vENRlFU4YbrwVqNDZ7fLvy+JR1CRkyr01jhSiDpE1u6py3OMzQfztQU2jxykW3ALNxO4kSlqIDeYyD0Y9RcQeQ==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@rollup/plugin-inject": {
       "version": "5.0.5",
       "dev": true,
@@ -3374,6 +3382,23 @@
       ],
       "peer": true
     },
+    "node_modules/@vitejs/plugin-vue": {
+      "version": "6.0.3",
+      "resolved": "https://registry.npmjs.org/@vitejs/plugin-vue/-/plugin-vue-6.0.3.tgz",
+      "integrity": "sha512-TlGPkLFLVOY3T7fZrwdvKpjprR3s4fxRln0ORDo1VQ7HHyxJwTlrjKU3kpVWTlaAjIEuCTokmjkZnr8Tpc925w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@rolldown/pluginutils": "1.0.0-beta.53"
+      },
+      "engines": {
+        "node": "^20.19.0 || >=22.12.0"
+      },
+      "peerDependencies": {
+        "vite": "^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0-0",
+        "vue": "^3.2.25"
+      }
+    },
     "node_modules/@volar/language-core": {
       "version": "2.4.27",
       "dev": true,