Enhance CI configuration and testing setup - #127

- Modified E2E testing scripts in `package.json` to ensure the third argument for `start-server-and-test` is an npm script name, fixing issues in local and CI environments.
- Added a new section in `README.md` detailing the current state of test layers, including unit, integration, and E2E tests, along with coverage statistics and integration gaps.
- Updated `CHANGELOG.md` to document these changes and their impact on testing processes.

- Updated E2E testing scripts to run Cucumber tests via Node, improving compatibility on Windows and simplifying execution.
- Restored UID ownership for Synapse E2E data directory after configuration patching to ensure proper access to signing keys.
- Merged E2E environment files for streamlined configuration management.
- Enhanced CHANGELOG to document these updates and their implications for testing processes.

- Introduced new E2E login testing scripts to support isolated authentication scenarios, improving test coverage for login processes.
- Updated `package.json` to include new npm scripts for running login-specific E2E tests.
- Enhanced `README.md` with instructions for executing the new login tests.
- Refactored `useMatrixClient` to ensure that the localpart of the username is used during login, improving compatibility with various username formats.
- Updated environment configuration to support new login credentials and ensure proper setup for E2E tests.
- Documented these changes in the CHANGELOG to reflect the enhancements in E2E testing and login functionality.

- Added entries to CHANGELOG for recent improvements in E2E login functionality, including a shared `matrixClientTestDoubles` factory for unit tests.
- Implemented Vitest configuration changes to prevent mock races during tests, ensuring consistent test results.
- Enhanced E2E tests to include new scenarios for user presence and room unread states, improving overall test coverage.
- Introduced data-testid attributes in UI components to facilitate more reliable testing.
- Updated various test scripts to improve robustness and maintainability, including adjustments to timeout settings for better performance.

- Updated CHANGELOG to reflect recent improvements, including the quarantine of unstable E2E scenarios for dedicated follow-up.
- Refactored chat timeline utilities to introduce `isDecryptableChatMessageEvent` and `readChatMessageContent`, enhancing message handling for encrypted events.
- Improved typing indicator functionality by adding a sync handler for better responsiveness.
- Enhanced E2E tests with adjustments to timeout settings and added checks for visibility of UI elements, ensuring more robust testing.
- Updated test scripts to exclude WIP scenarios from the main test runs, streamlining the testing process.

- Added logging functionality to track steps during the seeding process, improving visibility into the execution flow.
- Enhanced error handling in the `run-synapse-e2e.mjs` script to provide clearer output when environment variables are missing.
- Updated `runtime-seed-synapse.mjs` to log significant actions, such as user registration and room creation, aiding in debugging and monitoring.
- Improved overall robustness of E2E tests by ensuring that critical steps are logged for better traceability.

- Updated the E2E seeding scripts to wait for both the registration API and versions endpoint to be ready before proceeding, improving reliability in CI environments.
- Implemented retry logic for transient errors during seed requests, enhancing robustness against network issues.
- Enhanced logging for better visibility into the seeding process and error handling, aiding in debugging and monitoring.
- Updated CHANGELOG to reflect these improvements and their impact on E2E testing processes.

- Updated the E2E seeding scripts to include enhanced error handling for transient seed failures, improving robustness during CI runs.
- Implemented logging for seed process failures and added a warm-up function for the registration API, ensuring readiness before proceeding with tests.
- Enhanced the `isSynapseReadyForSeed` function to probe both client registration and shared-secret endpoints, improving readiness checks.
- Updated CHANGELOG to reflect these enhancements and their impact on E2E testing processes.

…handling

- Updated the `isSynapseReadyForSeed` function to utilize a timeout mechanism for fetching readiness status, enhancing reliability during CI runs.
- Removed the warm-up function for the registration API, streamlining the seeding process while ensuring readiness through improved checks.
- Enhanced error handling in the seeding scripts to better manage transient errors and improve logging for debugging.
- Updated CHANGELOG to reflect these changes and their impact on E2E testing processes.

- Added detailed guidelines for logging user-visible changes in the CHANGELOG, emphasizing the correct placement and formatting of entries under `[Unreleased]`.
- Updated the issue documentation checklist to reflect the new requirements for CHANGELOG entries, ensuring clarity on how to document changes effectively.