feat(frontend): unify feed/result state flow

[gildesmarais]

Summary

• unify guest/member/result flow around a consistent dominant-field interaction model
• refine app panels and result display behavior for readiness and retry states
• align related frontend hooks/api wiring and test coverage with the updated UI state contract
• rename frontend type entrypoint from env.d.ts to environment.d.ts

This pull request updates and improves the frontend test suites for the application, focusing on consistency in terminology, better test reliability, and improved clarity in test expectations. The changes include standardizing user-facing text in tests, switching from window to globalThis for global objects, and updating test logic to match recent UI and API changes.

Most important changes:

Terminology and Text Consistency:

• Standardized the access token prompt from "Add access token" to "Enter access token" across all relevant tests, ensuring consistency with the application's UI. [1] [2] [3] [4]
• Updated test expectations to use new user-facing messages, such as changing "Feed generation failed" to "Could not create feed link", "Your feed is ready" to "Feed ready", and other similar updates for clarity and consistency. [1] [2] [3] [4] [5]

Test Reliability and Modernization:

• Replaced usage of window with globalThis for accessing global objects like localStorage and history in tests, improving compatibility and reliability in different testing environments. [1] [2] [3] [4] [5]
• Changed test selectors from document.getElementById to document.querySelector for improved robustness and flexibility in selecting DOM elements. [1] [2] [3]

Test Data and Mocking Improvements:

• Updated all mock return values in tests to use undefined instead of null for uninitialized or missing values, aligning with current code conventions. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

UI and UX Flow Adjustments:

• Updated test logic to match new UI flows, such as changing error handling and retry button labels from "Try ... instead" to "Retry with ...", and updating messages about feed creation and readiness. [1] [2] [3]

Minor Test and Code Cleanups:

• Removed unused imports (e.g., h from preact) and improved array creation for utility items in tests for better readability. [1] [2]

These changes collectively improve test accuracy, maintainability, and ensure that tests reflect the current application behavior and user interface.