docs(os-dev): 自扫字符类补上 DEL,与 #5460 扩面后的门禁扫描面对齐 (#5484) (#5577)

`.claude/agents/os-dev.md` 的 Byte discipline 段要求 dev agent 在改动涉及
控制字符时「self-scan beyond the gate」,给出的字符类却停在 #5157 时代的
扫描面(C0 减 tab/LF/CR)。#5460(PR #5479)已把 `check:nul-bytes` 的扫描
面扩到含 DEL(0x7f),该指令未跟 —— 于是它成了门禁的真子集:agent 写下一枚
0x7f,按指令自扫绿,推上去 CI 红,把本可本地一秒发现的问题推迟整个 CI 轮次,
恰好在这条指令唯一被设计来防的场景里给出假绿。

改动一行,字符类与门禁脚本头的 `[\x00-\x08\x0b\x0c\x0e-\x1f\x7f]` 一致。
「同一事实手抄三处」的单源化根治方向留在 #5484 正文,不在本单实施。


Claude-Session: https://claude.ai/code/session_01GX3sL71LFq8m2usg6VqTSE

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-zhuang

.claude/agents/os-dev.md

@@ -271,7 +271,7 @@ binary: zero matches, no signal, and the rule you just wrote becomes
 invisible to every agent that greps for it. Run
 `node scripts/check-nul-bytes.mjs` before pushing, and when your change so
 much as *mentions* control characters, self-scan beyond the gate
-(`grep -naP '[\x00-\x08\x0b\x0c\x0e-\x1f]' <files>`) — the gate's blind
+(`grep -naP '[\x00-\x08\x0b\x0c\x0e-\x1f\x7f]' <files>`) — the gate's blind
 spots are exactly where these bytes hide.
 
 The GitHub body sanitizer is the same discipline's other half: it strips `<`