refactor(form-schema): extract schema types and schema-driven behaviors to shared package

Moves formBuilder types, formValidation, useConditionalLogic, useFormSteps,
and formatFieldValue from apps/portal/src to packages/form-schema/src.
Adds @form-schema path alias to both apps/portal and apps/app.
Vue field components remain per-app to allow independent visual evolution.
Behavior-neutral: all 35 Vitest tests green.

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

apps/app/tsconfig.json

@@ -39,6 +39,12 @@
       ],
       "@validators": [
         "./src/@core/utils/validators"
+      ],
+      "@form-schema/*": [
+        "../../packages/form-schema/src/*"
+      ],
+      "vue": [
+        "./node_modules/vue"
       ]
     },
     "lib": [
@@ -63,7 +69,8 @@
     "./src/**/*.vue",
     "./themeConfig.ts",
     "./auto-imports.d.ts",
-    "./components.d.ts"
+    "./components.d.ts",
+    "../../packages/form-schema/src/**/*"
   ],
   "exclude": [
     "./dist",