migration: Add machine_id column to hosts table

- Adds machine_id as unique identifier for hosts
- Migrates existing hosts with 'migrated-' prefix
- Removes unique constraint from friendly_name
- Adds indexes for performance

backend/prisma/migrations/20251004090459_add_machine_id_to_hosts/migration.sql

@@ -0,0 +1,17 @@
+-- Add machine_id column as nullable first
+ALTER TABLE "hosts" ADD COLUMN "machine_id" TEXT;
+
+-- Generate machine_ids for existing hosts using their API ID as a fallback
+UPDATE "hosts" SET "machine_id" = 'migrated-' || "api_id" WHERE "machine_id" IS NULL;
+
+-- Remove the unique constraint from friendly_name
+ALTER TABLE "hosts" DROP CONSTRAINT IF EXISTS "hosts_friendly_name_key";
+
+-- Now make machine_id NOT NULL and add unique constraint
+ALTER TABLE "hosts" ALTER COLUMN "machine_id" SET NOT NULL;
+ALTER TABLE "hosts" ADD CONSTRAINT "hosts_machine_id_key" UNIQUE ("machine_id");
+
+-- Create indexes for better query performance
+CREATE INDEX "hosts_machine_id_idx" ON "hosts"("machine_id");
+CREATE INDEX "hosts_friendly_name_idx" ON "hosts"("friendly_name");
+