feat: add acquisition API foundation

Add acquisition persistence, cost-basis calculation, seller-scoped admin routes, contracts, validation, migration, and focused application/HTTP tests.

database/migrations/0014_acquisitions.sql

@@ -0,0 +1,19 @@
+CREATE TABLE "acquisitions" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"inventory_item_id" uuid NOT NULL REFERENCES "inventory_items"("id"),
+	"method" text NOT NULL,
+	"cost_minor" integer NOT NULL,
+	"currency" text NOT NULL,
+	"date" text,
+	"source" text,
+	"location" text,
+	"shipping_minor" integer DEFAULT 0 NOT NULL,
+	"tax_minor" integer DEFAULT 0 NOT NULL,
+	"other_fees_minor" integer DEFAULT 0 NOT NULL,
+	"estimated_trade_value_minor" integer DEFAULT 0 NOT NULL,
+	"notes" text,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	"updated_at" timestamp with time zone DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+CREATE INDEX "acquisitions_inventory_item_id_index" ON "acquisitions" USING btree ("inventory_item_id");

database/migrations/meta/_journal.json

@@ -99,6 +99,13 @@
       "when": 1789718400000,
       "tag": "0013_void_sales",
       "breakpoints": true
+    },
+    {
+      "idx": 14,
+      "version": "7",
+      "when": 1789804800000,
+      "tag": "0014_acquisitions",
+      "breakpoints": true
     }
   ]
 }