Add list layout option for Subscriptions page

[Harshil7875]

Add list layout option for Subscriptions page

This PR adds an optional list layout for the YouTube Subscriptions feed.

Feature

When enabled, the subscriptions page switches from the default grid layout to a vertical list layout where:

• thumbnails appear on the left
• title, channel, and metadata appear on the right

Implementation

The implementation follows the existing ImprovedTube architecture using a settings toggle that activates CSS rules.

Changes:

• general.js – adds the subscriptions_list_layout toggle
• messages.json – adds translation for "List layout on Subscriptions page"
• styles.css – converts the subscriptions grid into a single-column list layout

Key CSS behavior:

• activates only on /feed/subscriptions
• flattens ytd-rich-grid-row using display: contents
• converts the grid into a vertical flex layout
• hides placeholder items
• sets thumbnails to a fixed width and aligns metadata to the right

Testing

1. Load the extension via chrome://extensions → Load unpacked
2. Open https://www.youtube.com/feed/subscriptions
3. Enable "List layout on Subscriptions page" in ImprovedTube settings

The feed should switch from grid tiles to a horizontal list layout.

Notes

There is currently one unrelated failing test (test-large-playlist-fix.js) that references window.location in the Node test environment. This appears to be a pre-existing issue and is unrelated to this change.

Closes #3706

[ImprovedTube]

thank you! @Harshil7875

Related: ImprovedTube: Thumbnails per row : 1

[envwarby]

Sounds awesome is the firefox extension also updated already? you only made mention of the chrome one.