docs(packaging): M129 r1 P1-1 —— MSA 那段改成 GUI 现有行为，不再写「界面会告诉你怎么配」

复审 r1 把链路走了一遍：core 缺 id 早退（零网络）成立，但 presenter 的 fail() 只把原文
eprintln 进日志，事件只带原因码 Other；账户页据此画通用横幅「Sign-in failed」+「Code: other」，
完整原因在日志里。LaunchMsaNotConfigured 那条 i18n 目前只有定义/单测/golden，GUI 零调用点。
所以上一版「the app says "not configured" (with the command to fix it)」是把设计意图写成了现有行为。

改成分段如实描述：无 id 时在联网之前就停；GUI 显示通用横幅 + Code: other（原因在日志）；
`ull accounts add msa` 会打出可照抄的修复命令（map_auth_error 的 hint，含变量名与 cargo build）。
另按 r1 P2-1 给 macOS 补 shasum 校验行（sha256sum 不是 macOS 自带）。

packaging/release-notes.md

@@ -76,7 +76,8 @@ adapter is present; `--software-renderer` (or its equivalent `--renderer=cpu`) f
 ## Verify the download
 
 ```bash
-sha256sum -c SHA256SUMS.txt --ignore-missing   # Linux / macOS
+sha256sum -c SHA256SUMS.txt --ignore-missing   # Linux
+shasum -a 256 -c SHA256SUMS.txt                # macOS (sha256sum is not bundled)
 Get-FileHash .\unlucky-launcher_{{VERSION}}_windows_x64.exe -Algorithm SHA256   # Windows PowerShell
 ```
 
@@ -87,9 +88,10 @@ Get-FileHash .\unlucky-launcher_{{VERSION}}_windows_x64.exe -Algorithm SHA256
 ## Known limitations of this build
 
 - Microsoft (MSA) sign-in needs an Azure public client id, and release binaries do not carry one: set
-  `ULL_MSA_CLIENT_ID=<id>` before launching, or build with that variable set. Until then the app says
-  "not configured" (with the command to fix it) instead of failing silently. Offline profiles and
-  authlib-injector servers need no id.
+  `ULL_MSA_CLIENT_ID=<id>` before launching, or build with that variable set. Without it sign-in stops
+  before any network call; in the GUI that shows up as the generic "Sign-in failed" banner with
+  `Code: other` (the full reason goes to the launcher log), and `ull accounts add msa` prints the exact
+  fix. Offline profiles and authlib-injector servers need no id.
 - Binaries are not code-signed / notarized yet: Windows SmartScreen and macOS Gatekeeper warn on first
   launch. The checksums above are the integrity reference for now.
 - macOS ships the bare binary (single-file promise), not a `.app` bundle: no Dock icon or Finder