Support Rutube via video services

[Vsnegovik]

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Tested on Chrome 147.0.7727.56

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Summary

This PR adds initial Rutube support through a new videoServices abstraction.

Rutube-specific logic is isolated under src/videoServices/rutube, while the parent module only selects the active service. This keeps the existing YouTube flow mostly untouched and gives us a place to add other services later.

What changed

• Added Rutube page detection and video ID parsing
• Added Rutube segment fetch/submit support
• Added Rutube player UI integration
• Added Rutube domains and the API domain to the manifest

API note

Rutube support currently uses sponsorblock.futuba.ru, which is a third-party API and not the official SponsorBlock backend.

The API server idea was based on the existing SponsorBlock for Rutube userscript published on Greasy Fork.

Because this third-party API does not support SponsorBlock categories or voting, all Rutube segments are currently displayed with the same color, even when different categories are selected, and segment voting is disabled.

This is the main review question: whether this dependency is acceptable.

Permissions impact

This PR adds new required host permissions for Rutube pages and sponsorblock.futuba.ru, and injects the content script on Rutube pages.

This increases the extension permission surface. To avoid forcing these permissions onto all users, we can make Rutube optional or ship a separate build.

Possible compromises

• Use the third-party Futuba API
• Use the official SponsorBlock API for Rutube if storing Rutube data there is acceptable to you
• Release two extension variants: YouTube-only and Rutube-only

Closes #1787