feature: clinic & lab invitation flow added. minimal ui implemented for organizations tab.

backend/prisma/schema.prisma

@@ -21,6 +21,7 @@ model User {
   ownedOrganizations Organization[] @relation("OrganizationOwner")
   sessions           Session[] // 👈 ADD THIS - opposite relation for Session
   sentStaffInvites   StaffInvitation[]
+  sentOrganizationInvitations OrganizationInvitation[]
 
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
@@ -57,6 +58,7 @@ model Organization {
 
   sharedWithMe     OrganizationLink[] @relation("OrganizationB")
   sharedWithOthers OrganizationLink[] @relation("OrganizationA")
+  sentOrganizationInvitations OrganizationInvitation[] @relation("OrganizationInvitationInviter")
   patients         Patient[]
 
   createdAt DateTime @default(now())
@@ -211,6 +213,32 @@ model OrganizationLink {
   @@map("organization_links")
 }
 
+model OrganizationInvitation {
+  id String @id @default(uuid())
+
+  inviterOrganizationId String
+  inviterUserId         String
+
+  invitedOrganizationId   String?
+  invitedOrganizationName String
+  invitedOwnerEmail       String
+  invitedOrganizationType String
+  tokenHash               String   @unique
+  expiresAt               DateTime
+  acceptedAt              DateTime?
+  revokedAt               DateTime?
+
+  inviterOrganization Organization @relation("OrganizationInvitationInviter", fields: [inviterOrganizationId], references: [id], onDelete: Cascade)
+  inviterUser         User         @relation(fields: [inviterUserId], references: [id], onDelete: Cascade)
+
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@index([inviterOrganizationId, createdAt])
+  @@index([invitedOwnerEmail, createdAt])
+  @@map("organization_invitations")
+}
+
 model Session {
   id           String   @id @default(uuid())
   userId       String