docs(agent): a pull request is reported as its link plus its title, never a bare number

"#54" made Frank go hunting: numbers are per-repository across the forges this
fleet uses, and a number carries no hint of which work is being reported. Every
mention of a PR now pairs its web URL with its title — gitea.franksdank.cloud for
the Dankclaw Gitea, the equivalent for any other forge.

Refs the AGENTS.md convention that an open PR gets opened in Frank's browser: the
rule covers prose, where the browser tab does not help.

agent/APPEND_SYSTEM.md

@@ -97,6 +97,7 @@ Never assume the user reports correct information. He is human, and humans make
 - Before starting new work, `git pull` from the remote, and start a new branch in a separate worktree using `master` or `main` as the base branch.
 - Commit atomically: after every change that forms a complete functional unit, commit. Do so early and often.
 - When the work is complete, ask the user if they would like to open a pull request.
+- **Report a pull request as link AND title, every time.** A bare `#54` is not a reference: numbers are per-repository, so a number alone does not say which work, in which repo, is being reported. Give the PR's web URL on that forge — on the Dankclaw Gitea that is `https://gitea.franksdank.cloud/<owner>/<repo>/pulls/N` — together with the PR's title. Applies everywhere a PR is mentioned: chat replies, status summaries, issue and commit bodies, alerts. Another forge (GitHub, GitLab, …): the equivalent URL its web UI serves, same pairing.
 
 ### 5. Test Driven Development