fix(just): replace Unicode in Windows PowerShell recipe strings

[githubrobbi]

Root cause

Windows PowerShell 5.1 (powershell.exe) reads UTF-8-no-BOM files as the system ANSI code page (CP1252). just writes #!powershell recipe bodies as UTF-8 without a BOM, so any multi-byte Unicode codepoint whose UTF-8 continuation byte lands in 0x91-0x94 decodes as a smart quotation mark (U+2018-U+201D), which the PowerShell tokenizer treats as a string delimiter. This silently terminates string literals mid-line and surfaces downstream as Unexpected token / Missing closing } errors far from the real cause.

Reported failure

> just bake-day
At C:\Users\rnio\AppData\Local\Temp\just-8Y4WhE\bake-day.ps1:259 char:1
+ } else {
+ ~
Unexpected token "}" in expression or statement.
error: Recipe `bake-day` failed with exit code 1

Line 259 of just/dev.just contains } else {. The actual breakage is upstream: the em-dash — (UTF-8 E2 80 94) on line 227 decodes to â€" under CP1252; the trailing 0x94 byte is U+201D (right double quote) which terminates the surrounding "..." string early, leaving PowerShell to mis-parse everything until it gives up at the next }.

Affected recipes

• just/dev.just::bake-day (the reported failure)
• just/dev.just::update-tools (same trap, same file)
• just/build.just::sync (em-dash on line 548)

Fix

Replaced all Unicode in [windows] #!powershell string literals with ASCII tags ([OK], [FAIL], [WARN], [TIP], [DONE], [Rust], [Pkg], etc.). Unicode in # comments was left intact — the tokenizer skips comment bodies. Unix recipe variants are unchanged.

Added a comment block above set windows-shell in just/shared.just documenting:

• The CP1252/UTF-8 trap with the exact byte sequences
• The ASCII-only rule for future Windows recipes
• Why we can't just switch to PowerShell 7 (operator baseline)

Verification

• just --evaluate parses clean on Mac
• Byte-scanner confirms 0 dangerous bytes (0x91-0x94) in any PowerShell string across all just/*.just files
• Full pre-push gate (22 jobs, including lint-ci-windows) passed locally

Test plan

• just bake-day runs to completion on Windows (was the reported failure)
• just update-tools parses on Windows
• just sync parses on Windows