Add Zen button in left navigation, settings import/export, and extend filtering

[quasa0]

TL;DR

Adds a Zen Writer Mode toggle directly to the X/Twitter left navigation, adds settings import/export controls to the extension popup, and extends the existing suggestions filtering so it also hides in-feed “Who to follow” blocks.

What changed?

• Added a persistent “Zen Writer Mode” button to the X/Twitter left navigation
• Reused the existing writerMode setting so the sidebar button and popup toggle stay in sync
• Added an active visual state for the Zen button when writer mode is enabled
• Added a Left Navigation setting to show or hide the Zen Writer Mode button like the other sidebar buttons

• Added settings export/import buttons at the bottom of the popup menu
• Exported settings include all known settings, merged with defaults, in a portable JSON file
• Imported settings are filtered to known setting keys before writing to extension storage

• Extended the existing removeTopicsToFollow setting to also hide in-feed “Who to follow” suggestion modules

• Added storage guards so stale content scripts from an extension reload do not throw uncaught storage errors

How to test?

1. Load the unpacked Chrome bundle and open X/Twitter
2. Verify the “Zen Writer Mode” button appears in the left navigation
3. Click the Zen button and confirm writer mode toggles on/off
4. Refresh the X/Twitter page and confirm the Zen button still reflects the current writer mode state
5. Open the extension popup and toggle the new “Zen Mode” control in Left Navigation
6. Confirm the Zen Writer Mode button can be hidden and shown again from that control
7. Confirm “Export Settings” and “Import Settings” appear at the bottom of the menu
8. Export settings and verify a minimal-twitter-settings.json file downloads
9. Import the exported file and confirm settings are restored without changing unknown keys
10. Enable “Topics to Follow Suggestions” filtering and confirm in-feed “Who to follow” modules are hidden
11. Reload the unpacked extension and refresh X/Twitter to confirm the extension continues to run cleanly

Why make this change?

Zen Writer Mode is one of the extension’s most useful focus controls, but it currently requires opening the popup to toggle. Putting it in the left navigation makes it available where users are already working, while the new Left Navigation setting keeps the button optional for users who want a stricter sidebar.

Settings import/export makes it easier to move between Chrome Store and unpacked builds, back up a customized setup, or reproduce a configuration while testing.

Extending the existing suggestions filter keeps the intent of the current setting intact: when users ask Minimal Twitter to remove distracting suggestion modules, the in-feed “Who to follow” surface should be removed too.

[quasa0]

Hey @linuz90 @frankdilo could one of you review please? Thanks!