Add comprehensive test suite for response and UI components

[f3l1x]

This PR adds a comprehensive test suite covering multiple response types and UI components in the Contributte Application library.

Summary

Added 7 new test files with extensive test coverage for response classes and UI components, ensuring proper functionality of PSR-7 stream responses, file responses with adapters, image responses, and null components.

Key Changes

• PSR7StreamResponse tests: Validates default/custom content types, getters, stream output, and empty stream handling
• FlyFileResponse tests: Tests adapter integration, content type configuration, filename changes, and download disposition settings
• StdoutAdapter tests: Verifies buffer writing, callback parameter passing, and output generation
• ProcessAdapter tests: Tests command execution, custom buffer sizes, and multi-line output handling
• ImageResponse tests: Validates constructor with Image instances, file paths, error handling, and custom type/quality parameters
• NullComponent tests: Confirms instantiation and proper inheritance from Nette Component

Notable Implementation Details

• Tests use mock implementations (e.g., anonymous StreamInterface class) to avoid external dependencies
• Comprehensive coverage of both success paths and edge cases (empty streams, non-existent files)
• Tests verify proper parameter passing between components and adapters
• Output buffering used to validate stream and process output

https://claude.ai/code/session_01JpmfUCxQwgqBnP1KzzbGLL

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