refactor(ci): split the issue analyst out and brief the review job from a file

The issue analyst moves verbatim from claude-bot.yml into its own
claude-issue-analyst.yml, so claude-bot.yml now holds only the pull-request
side: review, @claude mentions and conflict resolution.

The review job's briefing was a single 2,600-character quoted string inside
claude_args, unreadable and unreviewable. It now lives in
.github/claude/review-job.md, assembled at run time with a "This run"
section that hands the reviewer the pinned head SHA, the pull request and
the exact check-runs command, and reaches the CLI through
--append-system-prompt-file. The agent-mode action sets no system-prompt
append of its own, so the file flag cannot collide with one.

Findings no longer carry the fix: REVIEW.md and the brief both forbid
suggestion blocks, patches and replacement snippets, overriding the
code-review skill's --comment step, which attaches a committable suggestion
to any small fix. A finding states what is wrong, where, what triggers it
and what breaks; the maintainer decides the change.

docs/architecture.md

@@ -285,7 +285,8 @@ 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-bot.yml,
+                              #     claude-issue-analyst.yml
 ```
 
 ---
@@ -573,7 +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` (issue bot).
+(multi-arch image + release builds), `cleanup_caches.yml`, `claude-bot.yml` (PR review,
+`@claude` mentions, conflict resolution), `claude-issue-analyst.yml` (issue triage).
 
 ---