refactor: improve test coverage and support both X11 and Wayland plat…

[bigr]

…forms

Test Improvements:

• Add CLI tests for Firefox rejection with helpful error messages
• Add CLI tests for invalid browser rejection
• Add integration tests for ozone platform defaults
• Add integration tests for custom ozone platform via chrome flags
• Tests now catch platform compatibility issues early

Platform Support:

• Change default ozone platform from "auto" to "x11" for better compatibility
• Add support for custom ozone platform via --chrome-flags "ozone-platform=wayland"
• Update chrome flags parser to handle ozone-platform parameter
• Now supports both X11 and Wayland with explicit configuration

Why Tests Didn't Catch This:

• Previous tests only checked template rendering, not default values
• No integration tests for wrapper script content
• No tests for chrome flags parsing
• Platform-specific issues only manifest at runtime

New Tests:

• test_add_command_firefox_not_supported: Validates Firefox rejection
• test_add_command_invalid_browser: Validates invalid browser rejection
• test_add_uses_x11_ozone_platform_by_default: Validates X11 default
• test_add_allows_custom_ozone_platform: Validates Wayland override

Usage:

# Default: X11 (works on most systems)
pwa-forge add [https://example.com](https://example.com)

# Wayland support
pwa-forge add [https://example.com](https://example.com) --chrome-flags "ozone-platform=wayland"