feat(invoice): implement atomic invoice tools (REFACTOR-3)

- Add create_invoice_draft, add_invoice_line, update_invoice_line, delete_invoice_line, set_invoice_project, validate_invoice tools
- Update DolibarrClient with corresponding methods
- Add tests for atomic invoice operations
- Update development docs with venv instructions

tests/test_invoice_atomic.py

@@ -0,0 +1,90 @@
+import pytest
+from unittest.mock import AsyncMock, patch
+from dolibarr_mcp.config import Config
+from dolibarr_mcp.dolibarr_client import DolibarrClient
+
+@pytest.mark.asyncio
+class TestInvoiceAtomic:
+    
+    @pytest.fixture
+    def client(self):
+        config = Config(
+            dolibarr_url="https://test.dolibarr.com/api/index.php",
+            api_key="test_key"
+        )
+        return DolibarrClient(config)
+
+    @patch('aiohttp.ClientSession.request')
+    async def test_add_invoice_line(self, mock_request, client):
+        mock_response = AsyncMock()
+        mock_response.status = 200
+        mock_response.text.return_value = '123' # Returns line ID usually
+        mock_request.return_value.__aenter__.return_value = mock_response
+
+        async with client:
+            await client.add_invoice_line(
+                invoice_id=1,
+                desc="Test Line",
+                qty=1,
+                subprice=100,
+                product_id=99
+            )
+
+        # Verify call
+        args, kwargs = mock_request.call_args
+        assert args[0] == "POST"
+        assert args[1] == "https://test.dolibarr.com/api/index.php/invoices/1/lines"
+        assert kwargs['json'] == {
+            "desc": "Test Line",
+            "qty": 1,
+            "subprice": 100,
+            "fk_product": 99
+        }
+
+    @patch('aiohttp.ClientSession.request')
+    async def test_update_invoice_line(self, mock_request, client):
+        mock_response = AsyncMock()
+        mock_response.status = 200
+        mock_response.text.return_value = '{"success": 1}'
+        mock_request.return_value.__aenter__.return_value = mock_response
+
+        async with client:
+            await client.update_invoice_line(
+                invoice_id=1,
+                line_id=10,
+                qty=5
+            )
+
+        args, kwargs = mock_request.call_args
+        assert args[0] == "PUT"
+        assert args[1] == "https://test.dolibarr.com/api/index.php/invoices/1/lines/10"
+        assert kwargs['json'] == {"qty": 5}
+
+    @patch('aiohttp.ClientSession.request')
+    async def test_delete_invoice_line(self, mock_request, client):
+        mock_response = AsyncMock()
+        mock_response.status = 200
+        mock_response.text.return_value = '{"success": 1}'
+        mock_request.return_value.__aenter__.return_value = mock_response
+
+        async with client:
+            await client.delete_invoice_line(invoice_id=1, line_id=10)
+
+        args, kwargs = mock_request.call_args
+        assert args[0] == "DELETE"
+        assert args[1] == "https://test.dolibarr.com/api/index.php/invoices/1/lines/10"
+
+    @patch('aiohttp.ClientSession.request')
+    async def test_validate_invoice(self, mock_request, client):
+        mock_response = AsyncMock()
+        mock_response.status = 200
+        mock_response.text.return_value = '{"success": 1}'
+        mock_request.return_value.__aenter__.return_value = mock_response
+
+        async with client:
+            await client.validate_invoice(invoice_id=1, warehouse_id=5)
+
+        args, kwargs = mock_request.call_args
+        assert args[0] == "POST"
+        assert args[1] == "https://test.dolibarr.com/api/index.php/invoices/1/validate"
+        assert kwargs['json'] == {"idwarehouse": 5, "not_trigger": 0}