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.

docs/architecture.md

@@ -285,7 +285,7 @@ node heartbeat every 5s, periodic traffic resets (hourly/daily/weekly/monthly).
 ├── x-ui.service.*  / x-ui.rc                               # systemd units (debian/rhel/arch) + rc script
 ├── windows_files/                                          # Windows service support
 └── .github/workflows/        # CI: ci.yml, codeql.yml, docker.yml, release.yml, smoke.yml,
-                              #     mutation.yml, cleanup_caches.yml, claude-bot.yml,
+                              #     mutation.yml, cleanup_caches.yml, claude-pr-review.yml,
                               #     claude-issue-analyst.yml
 ```
 
@@ -574,8 +574,8 @@ root → `go build ./...` / `go run main.go`.
 
 **CI** (`.github/workflows/`): `ci.yml` (build/test/lint), `codeql.yml` (security scan),
 `smoke.yml` (smoke tests), `mutation.yml` (mutation testing), `docker.yml` + `release.yml`
-(multi-arch image + release builds), `cleanup_caches.yml`, `claude-bot.yml` (PR review,
-`@claude` mentions, conflict resolution), `claude-issue-analyst.yml` (issue triage).
+(multi-arch image + release builds), `cleanup_caches.yml`, `claude-pr-review.yml` (PR review
+only - it changes no code), `claude-issue-analyst.yml` (issue triage).
 
 ---