Track comment content edits separately from reaction updates

[Copilot]

Comments were deriving their edited state from the document modified timestamp, so reaction changes surfaced as Edited. This change introduces an explicit content-edit timestamp for GP Comment and drives the UI from that field instead of generic document mutation time.

• Backend: explicit edit tracking

  • Added edited_at to GP Comment.
  • Set edited_at only when content changes on an existing comment.
  • Left reaction updates on normal document saves without treating them as content edits.

• UI: edited state reflects content changes only

  • Switched the comment header Edited label to use comment.edited_at.
  • Switched Revisions visibility to the same field, so revision affordances only appear after a real content edit.

• Data fetch/types

  • Included edited_at in comment list queries and GPComment typings so timeline consumers have the new source of truth.

• Migration

  • Added a backfill patch that derives edited_at from Version rows where the content field changed.
  • Registered the patch under gameplan/gameplan/doctype/gp_comment/patches/ and updated patches.txt to the new module path.

<Tooltip
  v-if="comment.edited_at"
  :text="dayjsLocal(comment.edited_at).format('D MMM YYYY [at] h:mm A')"
>
  <span class="text-ink-gray-5">&nbsp;&middot; Edited</span>
</Tooltip>

[cypress]

gameplan    Run #420

Run Properties:   Passed #420  •  7c5e2da6ed ℹ️: Merge 4a66c24f5d4ecd026affed0c1d154a97368e12c1 into 6e460704a09a0681423e623b30c5...

Project	gameplan
Branch Review	copilot/fix-comment-edited-notification
Run status	Passed #420
Run duration	00m 51s
Commit	7c5e2da6ed ℹ️: Merge 4a66c24f5d4ecd026affed0c1d154a97368e12c1 into 6e460704a09a0681423e623b30c5...
Committer	Copilot
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