Add external model persistence foundation

src/db/schema/external-model-sources.ts

@@ -0,0 +1,23 @@
+import { sqliteTable, text, uniqueIndex } from "drizzle-orm/sqlite-core";
+import { externalModelSourceTypes } from "../../external-model/domain/external-model-contracts.js";
+import { projects } from "./projects.js";
+
+export const externalModelSources = sqliteTable(
+  "external_model_sources",
+  {
+    id: text("id").primaryKey(),
+    projectId: text("project_id")
+      .notNull()
+      .references(() => projects.id, { onDelete: "cascade" }),
+    name: text("name").notNull(),
+    sourceType: text("source_type", { enum: externalModelSourceTypes })
+      .notNull()
+      .default("revit_csv"),
+  },
+  (table) => [
+    uniqueIndex("external_model_sources_project_type_unique").on(
+      table.projectId,
+      table.sourceType
+    ),
+  ]
+);