fix: restore Blazor WebAssembly render mode for ERP scalability

Restore long-term architectural goal: Blazor WebAssembly for admin UI.

Rationale:
- TaxBaik is a semi-project for future ERP implementation
- ERP requires client-side scalability (no server-side state per user)
- WebAssembly offloads interactivity to browser (Circuit-free)
- Aligns with API-First + stateless backend design

Changes:
- App.razor: InteractiveWebAssemblyRenderMode (prerender: true)
- Routes: InteractiveWebAssemblyRenderMode (prerender: true)
- Login.razor: InteractiveWebAssemblyRenderMode (prerender: true)
- Program.cs: AddInteractiveWebAssemblyComponents()
- Updated validation script to enforce WebAssembly mode

Tradeoff accepted: Blazor WebAssembly bootstrap time vs future ERP extensibility.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

scripts/validate_admin_render.sh

@@ -11,18 +11,18 @@ for file in "$app_file" "$login_file"; do
   fi
 done
 
-if ! grep -nE "InteractiveServerRenderMode\\(prerender: true\\)" "$app_file" >/dev/null; then
-  echo "Admin shell must use InteractiveServerRenderMode(prerender: true)." >&2
+if ! grep -nE "InteractiveWebAssemblyRenderMode\\(prerender: true\\)" "$app_file" >/dev/null; then
+  echo "Admin shell must use InteractiveWebAssemblyRenderMode(prerender: true)." >&2
   exit 1
 fi
 
-if grep -nE "InteractiveWebAssemblyRenderMode|prerender: true" "$app_file" | grep -v "InteractiveServerRenderMode(prerender: true)" >/dev/null; then
+if grep -nE "InteractiveServerRenderMode|prerender: true" "$app_file" | grep -v "InteractiveWebAssemblyRenderMode(prerender: true)" >/dev/null; then
   echo "Admin shell render mode violation detected." >&2
   exit 1
 fi
 
-if ! grep -nE "InteractiveServerRenderMode\\(prerender: true\\)" "$login_file" >/dev/null; then
-  echo "Login page must allow server prerender." >&2
+if ! grep -nE "InteractiveWebAssemblyRenderMode\\(prerender: true\\)" "$login_file" >/dev/null; then
+  echo "Login page must use InteractiveWebAssemblyRenderMode(prerender: true)." >&2
   exit 1
 fi