feat: add safe cross-platform upstream updater (#98)

* feat: add safe upstream update scripts

* fix(updater): use portable PowerShell temp path

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Co-authored-by: Wibias <37517432+Wibias@users.noreply.github.com>

scripts/update-banner.txt

@@ -0,0 +1,9 @@
+ ▄▄▄█████▓▓█████  ███▄ ▄███▓ ██▓███  ▓█████   ██████ ▄▄▄█████▓
+ ▓  ██▒ ▓▒▓█   ▀ ▓██▒▀█▀ ██▒▓██░  ██▒▓█   ▀ ▒██    ▒ ▓  ██▒ ▓▒
+ ▒ ▓██░ ▒░▒███   ▓██    ▓██░▓██░ ██▓▒▒███   ░ ▓██▄   ▒ ▓██░ ▒░
+ ░ ▓██▓ ░ ▒▓█  ▄ ▒██    ▒██ ▒██▄█▓▒ ▒▒▓█  ▄   ▒   ██▒░ ▓██▓ ░
+   ▒██▒ ░ ░▒████▒▒██▒   ░██▒▒██▒ ░  ░░▒████▒▒██████▒▒  ▒██▒ ░
+   ▒ ░░   ░░ ▒░ ░░ ▒░   ░  ░▒▓▒░ ░  ░░░ ▒░ ░▒ ▒▓▒ ▒ ░  ▒ ░░
+     ░     ░ ░  ░░  ░      ░░▒ ░      ░ ░  ░░ ░▒  ░ ░    ░
+   ░         ░   ░      ░   ░░          ░   ░  ░  ░    ░
+             ░  ░       ░               ░  ░      ░