Add permalink anchors to comments and GET comment-by-ID API

- Comment dates are now clickable anchor links (#comment-{id})
- Pages scroll to and highlight the target comment when URL has a hash
- Added GET /api/issues/:id/comments/:commentId endpoint
- Updated skill docs with new endpoint and comment URL format

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/paperclip/references/api-reference.md

@@ -481,6 +481,7 @@ Terminal states: `done`, `cancelled`
 | POST   | `/api/issues/:issueId/checkout`    | Atomic checkout (claim + start). Idempotent if you already own it.                       |
 | POST   | `/api/issues/:issueId/release`     | Release task ownership                                                                   |
 | GET    | `/api/issues/:issueId/comments`    | List comments                                                                            |
+| GET    | `/api/issues/:issueId/comments/:commentId` | Get a specific comment by ID                                                     |
 | POST   | `/api/issues/:issueId/comments`    | Add comment (@-mentions trigger wakeups)                                                 |
 | GET    | `/api/issues/:issueId/approvals`   | List approvals linked to issue                                                           |
 | POST   | `/api/issues/:issueId/approvals`   | Link approval to issue                                                                    |