Fix mobile video pages redirecting to homepage

[scarf005]

Summary

Fixes #629 - Video pages were redirecting to the homepage on all Android/mobile devices when BlockTube was active.

Root Cause

The redirectToNextMobile() function is configured as a customFunc for slimVideoMetadataSectionRenderer, which appears on every mobile video page. The function was being called for ALL videos but wasn't checking whether a video was actually blocked before executing its redirect/delete logic.

This caused ALL videos on mobile (m.youtube.com) to either:

• Have their content deleted if autoplay was disabled
• Redirect to another video if autoplay was enabled

Fix

Added a check at the start of redirectToNextMobile() to return early if currentBlock is false, ensuring the function only acts when a video has actually been blocked by the filter.

function redirectToNextMobile() {
  if (!currentBlock) {
    return false;
  }
  // ... rest of redirect logic
}

This matches the pattern used elsewhere in the codebase where currentBlock is checked before executing redirect logic (e.g., line 1097 in fetchFilter()).

Testing

• No syntax errors or diagnostics
• Minimal change (4 lines added)
• Preserves existing behavior for blocked videos
• Fixes the issue for non-blocked videos on mobile