feat(portal): public-form component architecture

Replace monolithic register/[eventSlug].vue with composable field
renderer, conditional-logic engine, stepper, and per-field components
driven by Form Builder schema. Adds flatpickr for date fields.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/portal/package.json

@@ -8,6 +8,8 @@
     "build": "vite build",
     "preview": "vite preview --port 5050",
     "typecheck": "vue-tsc --noEmit",
+    "test": "vitest run",
+    "test:watch": "vitest",
     "lint": "eslint . -c .eslintrc.cjs --fix --ext .ts,.js,.cjs,.vue,.tsx,.jsx",
     "build:icons": "tsx src/plugins/iconify/build-icons.ts",
     "msw:init": "msw init public/ --save",
@@ -36,6 +38,7 @@
     "cookie-es": "1.2.2",
     "destr": "2.0.5",
     "eslint-plugin-regexp": "2.10.0",
+    "flatpickr": "^4.6.13",
     "jwt-decode": "4.0.0",
     "mapbox-gl": "3.5.2",
     "ofetch": "1.5.0",
@@ -91,6 +94,7 @@
     "@typescript-eslint/parser": "7.18.0",
     "@vitejs/plugin-vue": "6.0.1",
     "@vitejs/plugin-vue-jsx": "5.1.1",
+    "@vue/test-utils": "^2.4.6",
     "eslint": "8.57.1",
     "eslint-config-airbnb-base": "15.0.0",
     "eslint-import-resolver-typescript": "3.10.1",
@@ -101,6 +105,7 @@
     "eslint-plugin-sonarjs": "0.24.0",
     "eslint-plugin-unicorn": "51.0.1",
     "eslint-plugin-vue": "9.33.0",
+    "jsdom": "^29.0.2",
     "msw": "2.6.8",
     "postcss-html": "1.8.0",
     "postcss-scss": "4.0.9",
@@ -121,6 +126,7 @@
     "vite-plugin-vue-meta-layouts": "0.6.1",
     "vite-plugin-vuetify": "2.1.2",
     "vite-svg-loader": "5.1.0",
+    "vitest": "^3.2.4",
     "vue-shepherd": "3.0.0",
     "vue-tsc": "3.1.2"
   },