Add comprehensive test coverage for extension and app

[rishabhcli]

JavaScript Tests (212 tests):

• rules.test.js: Validates all 6 declarativeNetRequest rules, regex patterns, and URL transformations
• background.test.js: Tests service worker message handling, storage operations, and ruleset management
• popup.test.js: Tests popup UI state management, Safari detection, and message passing
• content.test.js: Tests URL transformation logic, video ID extraction, and redirect behavior

Swift Tests:

• TintPaletteTests: Tests color enum values, Codable conformance, and all 3 tint options
• ExtensionIdentifiersTests: Validates bundle ID format and structure
• URLTransformationTests: Comprehensive video ID extraction from all URL formats
• ManifestValidationTests: Validates permissions and extension configuration
• VideoIDFormatTests: Tests video ID character validation
• PrivacyTests: Ensures no tracker domains in allowed list
• EdgeCaseTests: Tests empty URLs, fragments, special characters, HTTP/HTTPS

UI Tests:

• Tests app launch, main view appearance, and UI element visibility
• Tests status indicators, steps panel, support panel, diagnostics panel
• Tests action buttons, pills/badges, scrolling behavior
• Tests accessibility, orientation support, and performance