test: add comprehensive tests for tool workshop functionality

Backend tests:
- Unit tests for docker_build service (successful/failed builds, context, paths)
- Unit tests for readiness_probe service (success, timeout, retries, edge cases)
- Integration tests for config_folders API (CRUD + project overrides)
- Integration tests for tool_types API with new fields
- Integration tests for tool_configs API with new fields

Frontend tests:
- ToolWorkshopPage component tests (all 3 tabs, create/edit/delete)
- API client tests for tool_types and config_folders

Fixes:
- Add field_validator import to tool_configs.py
- Add JSON import to tool_config model
- Update frontend test button names to match UI (Create Tool Type, Add Config, Create Folder)

Quality gates: backend unit tests passing (23/23)

apps/api/tests/unit/test_docker_build.py

@@ -0,0 +1,151 @@
+"""Unit tests for docker build service."""
+
+import subprocess
+import tempfile
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from src.services.docker_build import build_image
+
+
+class TestBuildImage:
+    """Tests for build_image function."""
+
+    @patch("subprocess.run")
+    def test_builds_image_successfully(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(
+            returncode=0,
+            stdout="Successfully built abc123",
+            stderr="",
+        )
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result = build_image(tmpdir, "FROM python:3.11", "test-image:latest")
+            
+            assert result[0] == 0
+            assert "Successfully built" in result[1]
+            mock_run.assert_called_once()
+            call_args = mock_run.call_args
+            assert "test-image:latest" in call_args[0][0]
+            assert "build" in call_args[0][0]
+
+    @patch("subprocess.run")
+    def test_build_fails(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(
+            returncode=1,
+            stdout="",
+            stderr="Error: failed to build",
+        )
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result = build_image(tmpdir, "FROM invalid:image", "test-image:latest")
+            
+            assert result[0] == 1
+            assert "failed to build" in result[2]
+
+    @patch("subprocess.run")
+    def test_build_with_tag(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(
+            returncode=0,
+            stdout="",
+            stderr="",
+        )
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            build_image(tmpdir, "FROM python:3.11", "my-registry/tool:v1.0")
+            
+            call_args = mock_run.call_args[0][0]
+            assert "my-registry/tool:v1.0" in call_args
+
+    @patch("subprocess.run")
+    def test_build_command_structure(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(returncode=0, stdout="", stderr="")
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            build_image(tmpdir, "FROM python:3.11", "test:latest")
+            
+            cmd = mock_run.call_args[0][0]
+            assert cmd[0] == "docker"
+            assert cmd[1] == "build"
+            assert "-t" in cmd
+            assert "test:latest" in cmd
+            assert tmpdir in cmd
+
+    @patch("subprocess.run")
+    def test_build_writes_dockerfile(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(returncode=0, stdout="", stderr="")
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            dockerfile_content = "FROM python:3.11\\nRUN pip install flask"
+            build_image(tmpdir, dockerfile_content, "test:latest")
+            
+            dockerfile_path = Path(tmpdir) / "Dockerfile"
+            assert dockerfile_path.exists()
+            assert dockerfile_path.read_text() == dockerfile_content
+
+    @patch("subprocess.run")
+    def test_build_writes_context_files(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(returncode=0, stdout="", stderr="")
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            build_context = {
+                "requirements.txt": "flask==2.0\\nnumpy==1.21",
+                "app.py": "from flask import Flask\\napp = Flask(__name__)",
+            }
+            build_image(tmpdir, "FROM python:3.11", "test:latest", build_context)
+            
+            req_path = Path(tmpdir) / "requirements.txt"
+            app_path = Path(tmpdir) / "app.py"
+            assert req_path.exists()
+            assert req_path.read_text() == "flask==2.0\\nnumpy==1.21"
+            assert app_path.exists()
+            assert app_path.read_text() == "from flask import Flask\\napp = Flask(__name__)"
+
+    @patch("subprocess.run")
+    def test_build_creates_nested_directories(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(returncode=0, stdout="", stderr="")
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            build_context = {
+                "src/app.py": "print('hello')",
+            }
+            build_image(tmpdir, "FROM python:3.11", "test:latest", build_context)
+            
+            app_path = Path(tmpdir) / "src" / "app.py"
+            assert app_path.exists()
+
+    @patch("subprocess.run")
+    def test_build_prevents_path_traversal(self, mock_run) -> None:
+        mock_run.return_value = MagicMock(returncode=0, stdout="", stderr="")
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            build_context = {
+                "../../../etc/passwd": "root:x:0:0",
+            }
+            
+            with pytest.raises(ValueError, match="escapes instance directory"):
+                build_image(tmpdir, "FROM python:3.11", "test:latest", build_context)
+            
+            mock_run.assert_not_called()
+
+    @patch("subprocess.run")
+    def test_build_timeout(self, mock_run) -> None:
+        mock_run.side_effect = subprocess.TimeoutExpired(cmd=["docker", "build"], timeout=300)
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result = build_image(tmpdir, "FROM python:3.11", "test:latest")
+            
+            assert result[0] == 1
+            assert "timed out" in result[2].lower()
+
+    @patch("subprocess.run")
+    def test_build_exception(self, mock_run) -> None:
+        mock_run.side_effect = OSError("Docker not available")
+        
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result = build_image(tmpdir, "FROM python:3.11", "test:latest")
+            
+            assert result[0] == 1
+            assert "Docker not available" in result[2]