docs(pwsh-local): list the 5.1 non-ASCII stdin gap under Known Limitations (both languages)

packages/bash/pwsh-local/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/bash/pwsh-local/README.md
-README.md: e061d1bd614fa4aa13d3ae9418c2e4af47d72518
-README.zh.md: 3a8d2b7ea41c02dbaf72273b0e9ef0f2c023068f
+README.md: 76a30939d68ac866880f906b928b265628f4de1e
+README.zh.md: af98af1b83baa72ad8345362b583b61fa634d29a

packages/bash/pwsh-local/README.md

@@ -51,5 +51,6 @@ No direct invalidation; the named consumer owns any request-prefix changes.
 - **A background spawn-failure note is single-delivery** — the subprocess service buffers no output for a process that never ran, so the executor injects `spawn failed: …` into exactly one `readOutput()` delta; a reader that discards that delta cannot recover it.
 - **Windows termination reports no signal** — a force-killed process settles as exit 1 with `signal: null`, so signal-based status classification (POSIX `killed`) does not apply on Windows; `kill()`-initiated stops still stamp `killed` directly.
 - **The encoding preamble precedes the command** — PowerShell requires `param(...)`, `#requires`, and `using namespace`/`using assembly` statements at the very top of a script, so a command whose first statement is one of those cannot run under the UTF-8 output preamble. Wrap a `param(...)` script in `& { … }` (a param block legally heads a script block); `using` statements and `#requires` have no in-command workaround (`#requires` is inert inside `-Command` regardless of position) — run such scripts from a file instead.
+- **Non-ASCII stdin under Windows PowerShell 5.1 may be mis-decoded** — the preamble pins output encoding only; `[Console]::InputEncoding` stays at the host default because setting it under redirected stdin throws. pwsh 7 defaults to UTF-8 and is unaffected.
 
 Scrub-heuristic and spill-retention caveats live with [`dsh-subprocess-local`](../../subprocess/subprocess-local/README.md), which owns those mechanics.

packages/bash/pwsh-local/README.zh.md

@@ -51,5 +51,6 @@
 - **后台 spawn 失败提示只投递一次**——subprocess 服务不会为从未运行的进程缓冲输出，因此执行器只把 `spawn failed: …` 注入一次 `readOutput()` 增量；丢弃该增量的读取方无法恢复它。
 - **Windows 终止不报告信号**——被强制终止的进程以退出码 1、`signal: null` 结束，因此基于信号的状态分类（POSIX `killed`）在 Windows 上不适用；`kill()` 发起的停止仍会直接盖上 `killed`。
 - **编码 preamble 位于命令之前**——PowerShell 要求 `param(...)`、`#requires` 与 `using namespace`/`using assembly` 语句位于脚本最顶部，因此以其中一种开头的命令无法在 UTF-8 输出 preamble 下运行。`param(...)` 脚本可包进 `& { … }`（param 块可以合法地位于脚本块开头）；`using` 语句与 `#requires` 在命令内没有变通办法（`#requires` 在 `-Command` 中无论位置如何都不生效）——此类脚本请改从文件运行。
+- **Windows PowerShell 5.1 下的非 ASCII stdin 可能被错误解码**——preamble 只固定输出编码；`[Console]::InputEncoding` 保持主机默认，因为在重定向 stdin 下设置它会抛出异常。pwsh 7 默认 UTF-8，不受影响。
 
 清理启发式与 spill 保留的注意事项由 [`dsh-subprocess-local`](../../subprocess/subprocess-local/README.md) 持有，它拥有这些机制。