feat(commit_comment): Add inline comments on commit diffs

[brymut]

Resolves #4898
/claim #4898

Added ability to add inline comments on commit diffs. Using new commit_comment table and re-using the existing comment template and other existing functionality eg. Attachments & reactions.

Demo:

Screen.Recording.2025-11-07.at.17.44.35.mov

[lunny]

It also have the same problem as #32257 when the comments in the hidden lines.

[lunny]

Maybe we can have a reply_id?

[wxiaoguang]

Not only one or two fields, the table's design overall doesn't seem right. I have explained in discord.

[wxiaoguang]

It also have the same problem as #32257 when the comments in the hidden lines.

One more thing: "Add inline comments on commits #4898" requests the feature for "commits", but not for "commit diffs"

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By the way, I don't quite understand why this feature is that important or how end users can really use it, also quote my discord question:

I don't understand why that feature can be useful. For a repo with thousands of commits, a "commit comment" can be easily lost. For example, I also ever left some commit comments on GitHub, then I can never found them and I think there is no progress of them. So I don't know what it should look like or how to make it right.

And many voices in #4898 are talking about "comment on files directly (for student, education #4898 (comment))", not really "per commit".

Overall I don't see real use cases for such "commit level comments"