refactor(ci): make the Claude workflow review pull requests and nothing else

claude-bot.yml ran three jobs: the pull-request review, an @claude mention
responder, and a conflict resolver that committed and pushed to contributor
branches. Only the review is wanted, so the other two are gone and the file
is renamed to say what is left.

Consequences worth knowing:

- secrets.CLAUDE_BOT_PAT is no longer referenced by any workflow. It was the
  only push credential handed to an agent in this repository and can now be
  deleted from the repository settings.
- @claude goes unanswered everywhere. claude-issue-analyst.yml deliberately
  excludes mentions (!contains(body, '@claude')) so the two jobs would not
  both reply; with the mention job gone, only `@claude review` on a pull
  request still reaches anything. Dropping that clause from the analyst would
  restore mention answering on issues.
- The workflow display name changes, so a branch protection rule keyed on
  "Claude Bot / review" has to become "Claude PR Review / review". The job
  name, which is what statusCheckRollup reports, is unchanged.

The review job itself is byte-identical. The workflow-level permission drops
to issues: read, which is all the remaining job needs - it already declares
its own.

.github/claude/repo-context.md

@@ -3,8 +3,9 @@
 Briefing for the issue analyst in `.github/workflows/claude-issue-analyst.yml`.
 It exists so these facts live in ONE place next to the code instead of being
 restated in the prompt, where they went stale silently. (Pull-request review is
-separate: the code-review skill in `.github/workflows/claude-bot.yml` is briefed
-with `CLAUDE.md`, `REVIEW.md` and `.github/claude/review-job.md`, not this.)
+separate: the code-review skill in `.github/workflows/claude-pr-review.yml` is
+briefed with `CLAUDE.md`, `REVIEW.md` and `.github/claude/review-job.md`, not
+this.)
 
 `CLAUDE.md`, `frontend/CLAUDE.md` and `docs/architecture.md` outrank this file.
 Where they disagree with it, they win and this file is the thing to fix.

.github/claude/review-job.md

@@ -1,7 +1,7 @@
 # Review job briefing
 
 Appended to the system prompt of the pull-request review job in
-`.github/workflows/claude-bot.yml`. The workflow adds a "This run" section
+`.github/workflows/claude-pr-review.yml`. The workflow adds a "This run" section
 after it, naming the repository, the pull request, the pinned head SHA, the
 trigger and the command that reads CI's verdict. `REVIEW.md` at the repository
 root is the review rubric; this file only says how that rubric is applied in a