Work Items: Edit/Delete comments in timeline

[Flo0806]

Problem

Comments in the Work Item timeline (/work-items/ page) cannot be edited or deleted. The timeline uses CommentCard.vue which has no edit/delete UI — unlike the Issues page which uses IssueComment.vue with full edit/delete support.

Scope

1. Issue & PR comments (IssueComment type)

• Add edit/delete buttons to CommentCard.vue (or replace with IssueComment.vue pattern)
• Reuse existing PATCH /api/issues/comments and DELETE /api/issues/comments endpoints
• Respect viewerCanUpdate / viewerCanDelete from GraphQL (needs to be added to work item detail query)

2. PR review comments

• New endpoint: PATCH /api/pull-requests/review-comments (GitHub GraphQL updatePullRequestReviewComment)
• New endpoint: DELETE /api/pull-requests/review-comments (GitHub GraphQL deletePullRequestReviewComment)
• Add edit/delete UI to ReviewCommentThread.vue

3. PR/Issue body (initial comment)

• Reuse existing PATCH /api/issues/body endpoint
• Add edit button to the initial timeline entry

Notes

• Issues page will be removed — Work Items is the single view going forward
• useIssueDetail composable already has saveComment, removeComment, saveBody — wire these into the work item timeline