fix(GRO-982): look up or create client by phone before inserting conversation

Fixes FK constraint violation where clientId was set to businessSettings.id
or a random UUID. Now looks up clients.phone = clientPhone first; if no match,
creates a placeholder client with phone as name and a placeholder email.

apps/api/src/services/messaging/__tests__/inbound.test.ts

@@ -13,6 +13,7 @@ vi.mock("@groombook/db", () => ({
   conversations: { id: "", businessId: "", clientId: "", externalNumber: "", businessNumber: "", channel: "", lastMessageAt: null, status: "", createdAt: null, updatedAt: null },
   messages: { id: "", conversationId: "", direction: "", body: "", status: "", providerMessageId: "", sentByStaffId: null, createdAt: null, deliveredAt: null, readByClientAt: null },
   businessSettings: { id: "", messagingPhoneNumber: "" },
+  clients: { id: "", name: "", email: "", phone: "", status: "" },
   eq: vi.fn(),
   and: vi.fn(),
   sql: vi.fn(),
@@ -127,6 +128,33 @@ describe("findOrCreateConversation", () => {
     const result = await findOrCreateConversation("biz-1", "+1555111", "+1555222");
     expect(result.id).toBe("conv-2");
   });
+
+  it("creates placeholder client for unknown phone then creates conversation", async () => {
+    mockDb.select
+      .mockReturnValueOnce({
+        from: vi.fn().mockReturnValue({
+          where: vi.fn().mockReturnValue({
+            limit: vi.fn().mockReturnValue([]),
+          }),
+        }),
+      })
+      .mockReturnValueOnce({
+        from: vi.fn().mockReturnValue({
+          where: vi.fn().mockReturnValue({
+            limit: vi.fn().mockReturnValue([]),
+          }),
+        }),
+      });
+    mockDb.insert.mockReturnValue({
+      values: vi.fn().mockReturnValue({
+        returning: vi.fn().mockReturnValue([{ id: "conv-3", clientId: "client-3" }]),
+      }),
+    });
+
+    const result = await findOrCreateConversation("biz-1", "+1555111", "+1555222");
+    expect(result.id).toBe("conv-3");
+    expect(result.clientId).toBe("client-3");
+  });
 });
 
 describe("upsertMessage", () => {

apps/api/src/services/messaging/inbound.ts

@@ -1,4 +1,5 @@
-import { getDb, conversations, messages, businessSettings, eq, and, sql } from "@groombook/db";
+import { getDb, conversations, messages, businessSettings, clients, eq, and } from "@groombook/db";
+import { v4 as uuidv4 } from "uuid";
 
 export interface TelnyxMessageReceivedPayload {
   data: {
@@ -41,13 +42,23 @@ export async function findOrCreateConversation(
     return { id: existing.id, clientId: existing.clientId };
   }
 
-  const [business] = await db
+  const [existingClient] = await db
-    .select({ primaryClientId: sql<string>`${businessSettings.id}` })
+    .select({ id: clients.id })
-    .from(businessSettings)
+    .from(clients)
-    .where(eq(businessSettings.id, businessId))
+    .where(eq(clients.phone, clientPhone))
     .limit(1);
 
-  const clientId = business?.primaryClientId ?? crypto.randomUUID();
+  const clientId = existingClient?.id ?? uuidv4();
+
+  if (!existingClient) {
+    await db.insert(clients).values({
+      id: clientId,
+      name: clientPhone,
+      email: `sms-${uuidv4()}@placeholder.local`,
+      phone: clientPhone,
+      status: "active",
+    });
+  }
 
   const [created] = await db
     .insert(conversations)