feat: setup the attachment to the passenger api

apps/edr-passenger-api/prisma/migrations/20260717090000_support_chat_attachments/migration.sql

@@ -0,0 +1,39 @@
+-- Support chat attachments.
+--
+-- `SupportMessage.text` becomes nullable so an attachment-only message can say
+-- "there is no text" instead of smuggling that through an empty string. This is
+-- a catalog-only change in Postgres — no table rewrite, no long lock.
+ALTER TABLE "SupportMessage" ALTER COLUMN "text" DROP NOT NULL;
+
+-- The `attachments` JSONB column has been dead since the init migration: never
+-- written, never read, absent from every DTO. It is dropped rather than reused —
+-- an untyped blob gives no file identity, no size accounting, and nothing to
+-- cascade on delete. Real rows replace it below. (The name is also needed for
+-- the new relation.)
+ALTER TABLE "SupportMessage" DROP COLUMN "attachments";
+
+-- Backs keyset pagination of a thread (newest-first over (createdAt, id)).
+-- Without it, paging a long thread degrades to a scan per page.
+-- CreateIndex
+CREATE INDEX "SupportMessage_conversationId_createdAt_idx" ON "SupportMessage"("conversationId", "createdAt");
+
+-- CreateTable
+CREATE TABLE "SupportAttachment" (
+    "id" TEXT NOT NULL,
+    "messageId" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "mimeType" TEXT NOT NULL,
+    "size" INTEGER NOT NULL,
+    "url" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "SupportAttachment_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "SupportAttachment_messageId_idx" ON "SupportAttachment"("messageId");
+
+-- AddForeignKey
+-- CASCADE: an attachment has no meaning without its message. (Object bytes in
+-- MinIO are not reaped by this — deleting messages is not a flow that exists.)
+ALTER TABLE "SupportAttachment" ADD CONSTRAINT "SupportAttachment_messageId_fkey" FOREIGN KEY ("messageId") REFERENCES "SupportMessage"("id") ON DELETE CASCADE ON UPDATE CASCADE;