Skip video search results with invalid channel IDs

[Tyrrrz]

Closes #944

[Copilot]

Pull request overview

Fixes a crash in SearchClient when search results include video items with syntactically invalid channel IDs (e.g., "UC"), by validating/parsing the channel ID before constructing Author.

Changes:

• Add ChannelId.TryParse() validation for videoData.ChannelId in search video results.
• Skip video results whose channel ID cannot be parsed into a valid ChannelId.
• Construct Author using the parsed ChannelId value instead of relying on implicit conversion.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (76e7d56) to head (24f4591).
⚠️ Report is 1 commits behind head on prime.

Additional details and impacted files

@@     Coverage Diff      @@
##   prime   #945   +/-   ##
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