fix auth: register redirect, password reset flow, GHL contact ID, session handling

- Fix register redirect bug where successful signup returned 400 instead
  of redirecting to /account/setup (use isRedirect() to re-throw redirects)
- Add error display to register page and fix Svelte 5 syntax (on:click)
- Add await to Google sign-in on login page and register page
- Fix logout to await signOut and redirect to /
- Implement full password reset flow:
  - Add sendResetPassword callback to auth.ts config
  - Create forgot-password page with email submission
  - Create reset-password page with one-time token validation
  - Guard reset page: redirect to / if no valid token in URL
- Add ghlContactId field to Profile model for future Go High Level integration
- Add Prisma migration for ghl_contact_id column
- Update register test to expect redirect instead of broken 400

prisma/migrations/20260707132629_add_ghl_contact_id/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "Profile" ADD COLUMN     "ghl_contact_id" TEXT;

prisma/schema.prisma

@@ -36,13 +36,14 @@ model User {
 // I chose to create a Profile table here because honestly, I didn't want to waste
 // a bunch of time trying to figure out how to customize the default Better-Auth model. 
 model Profile {
-  id          String    @id @default(uuid())
-  userId      String    @unique
-  user        User      @relation(fields: [userId], references: [id], onDelete: Cascade)
-  firstName   String
-  lastName    String
-  phoneNumber String
-  addresses   Address[]
+  id           String    @id @default(uuid())
+  userId       String    @unique
+  user         User      @relation(fields: [userId], references: [id], onDelete: Cascade)
+  firstName    String
+  lastName     String
+  phoneNumber  String
+  ghlContactId String?   @map("ghl_contact_id")
+  addresses    Address[]
 }
 
 model Address {