(BE-58,,59): extend db schema & build stock transfer api

- Extend DB schema for stock transfers
- Build stock transfer API (create,)

internal/database/migrations/20251014024642_create_stock_transfer_details.up.sql

@@ -0,0 +1,49 @@
+-- ===============================================================
+--  STOCK TRANSFER DETAILS (PRODUK)
+-- ===============================================================
+
+CREATE TABLE IF NOT EXISTS stock_transfer_details (
+    id BIGSERIAL PRIMARY KEY,
+    stock_transfer_id BIGINT NOT NULL,
+    product_id BIGINT NOT NULL,
+    quantity NUMERIC(15, 3) NOT NULL CHECK (quantity > 0),
+    before_quantity NUMERIC(15, 3),
+    after_quantity NUMERIC(15, 3),
+    note TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    deleted_at TIMESTAMPTZ
+);
+
+-- ===============================================================
+--  FOREIGN KEYS (dengan pengecekan tabel agar anti gagal)
+-- ===============================================================
+
+DO $$
+BEGIN
+    IF EXISTS (SELECT 1 FROM pg_tables WHERE tablename = 'stock_transfers') THEN
+        EXECUTE
+        'ALTER TABLE stock_transfer_details
+         ADD CONSTRAINT fk_stock_transfer_details_transfer
+         FOREIGN KEY (stock_transfer_id)
+         REFERENCES stock_transfers(id)
+         ON DELETE CASCADE ON UPDATE CASCADE';
+    END IF;
+
+    IF EXISTS (SELECT 1 FROM pg_tables WHERE tablename = 'products') THEN
+        EXECUTE
+        'ALTER TABLE stock_transfer_details
+         ADD CONSTRAINT fk_stock_transfer_details_product
+         FOREIGN KEY (product_id)
+         REFERENCES products(id)
+         ON DELETE RESTRICT ON UPDATE CASCADE';
+    END IF;
+END $$;
+
+-- ===============================================================
+--  INDEXES
+-- ===============================================================
+
+CREATE INDEX IF NOT EXISTS idx_stock_transfer_details_transfer_id ON stock_transfer_details (stock_transfer_id);
+
+CREATE INDEX IF NOT EXISTS idx_stock_transfer_details_product_id ON stock_transfer_details (product_id);