Add comprehensive test suite with unit and integration tests

[Copilot]

Adds comprehensive test coverage for previously untested modules including handlers, API services, utilities, and integration workflows.

Test Files Added (84+ test methods)

Unit Tests

• test_handlers.py - Schema versioning event handler
• test_api_services.py - REST API services (/@json-schema, /@ui-schema, expandable elements)
• test_common_utils.py - Base path calculation, dependency validation invariants
• test_ct_option_list.py - OptionList content type with external API fetching, authentication, error handling
• test_viewlets.py - Developer viewlet rendering, schema retrieval, version management
• test_setuphandlers.py - Installation/uninstallation hooks
• test_view_utils.py - View registration and utilities
• test_schema_generation.py - JSON schema generation for all field types (text, email, URL, date, number), constraints, required fields

Integration Tests

• test_integration_forms.py - Complete form rendering with all field types, dependencies (OR/AND), show/hide conditions
• test_integration_wizard.py - Multi-step wizard navigation, nested forms, schema generation

Coverage Additions

Previously untested areas now covered:

• Event handlers for schema versioning on content modification
• REST API endpoint responses and schema structure
• External option list fetching with HTTP mocking
• Dependency validation across container boundaries (Form/Complex/Array/Fieldset)
• Schema generation edge cases (min/max constraints, format validation, nested objects)
• Wizard step management and navigation

Documentation

• docs/TEST_SUITE.md - Comprehensive test suite documentation
• src/edi/jsonforms/tests/README.md - Quick reference with examples

All tests follow existing plone.app.testing patterns, use appropriate test layers (INTEGRATION_TESTING, FUNCTIONAL_TESTING), and mock external dependencies.

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