feat: add inventory_category table and update inventory_items structure with category and unit references

backend/migrations/00008_modify_inventory_and_harvest_units.sql

@@ -0,0 +1,70 @@
+-- +goose Up
+-- Step 1: Create inventory_category table
+CREATE TABLE inventory_category (
+    id SERIAL PRIMARY KEY,
+    name TEXT NOT NULL UNIQUE
+);
+
+-- Step 2: Insert sample categories
+INSERT INTO inventory_category (name) 
+VALUES 
+    ('Seeds'),
+    ('Tools'),
+    ('Chemicals');
+
+-- Step 3: Add category_id column to inventory_items
+ALTER TABLE inventory_items
+ADD COLUMN category_id INT;
+
+-- Step 4: Link inventory_items to inventory_category
+ALTER TABLE inventory_items
+ADD CONSTRAINT fk_inventory_category FOREIGN KEY (category_id) REFERENCES inventory_category(id) ON DELETE SET NULL;
+
+-- Step 5: Remove old columns (type, category, unit) from inventory_items
+ALTER TABLE inventory_items
+DROP COLUMN type,
+DROP COLUMN category,
+DROP COLUMN unit;
+
+-- Step 6: Add unit_id column to inventory_items
+ALTER TABLE inventory_items
+ADD COLUMN unit_id INT;
+
+-- Step 7: Link inventory_items to harvest_units
+ALTER TABLE inventory_items
+ADD CONSTRAINT fk_inventory_unit FOREIGN KEY (unit_id) REFERENCES harvest_units(id) ON DELETE SET NULL;
+
+-- Step 8: Insert new unit values into harvest_units
+INSERT INTO harvest_units (name) 
+VALUES 
+    ('Tonne'),
+    ('KG');
+
+-- +goose Down
+-- Reverse Step 8: Remove inserted unit values
+DELETE FROM harvest_units WHERE name IN ('Tonne', 'KG');
+
+-- Reverse Step 7: Remove the foreign key constraint
+ALTER TABLE inventory_items
+DROP CONSTRAINT fk_inventory_unit;
+
+-- Reverse Step 6: Remove unit_id column from inventory_items
+ALTER TABLE inventory_items
+DROP COLUMN unit_id;
+
+-- Reverse Step 5: Add back type, category, and unit columns
+ALTER TABLE inventory_items
+ADD COLUMN type TEXT NOT NULL,
+ADD COLUMN category TEXT NOT NULL,
+ADD COLUMN unit TEXT NOT NULL;
+
+-- Reverse Step 4: Remove foreign key constraint from inventory_items
+ALTER TABLE inventory_items
+DROP CONSTRAINT fk_inventory_category;
+
+-- Reverse Step 3: Remove category_id column from inventory_items
+ALTER TABLE inventory_items
+DROP COLUMN category_id;
+
+-- Reverse Step 2: Drop inventory_category table
+DROP TABLE inventory_category;

frontend/app/(sidebar)/inventory/page.tsx

@@ -187,7 +187,7 @@ export default function InventoryPage() {
               </TableHeader>
               <TableBody>
                 {table.getRowModel().rows.map((row) => (
-                  <TableRow key={row.id}>
+                  <TableRow key={row.id} className="even:bg-gray-800">
                     {row.getVisibleCells().map((cell) => (
                       <TableCell key={cell.id}>
                         {flexRender(