fix(install): strip non-ASCII bytes from install.ps1 (unblocks self-update on cp1252 consoles)

[danielmeppiel]

TL;DR

Follow-up to #1522. The Windows CI apm self-update test (run 26543072369) fails with:

[x] Update failed: 'charmap' codec can't encode characters in position 33941-33942: character maps to <undefined>

install.ps1 contained two non-ASCII byte sequences -- an em-dash (pre-existing) and replacement chars I introduced in a comment. The v0.13.0 self-updater downloads install.ps1 via Python urllib and prints it through a cp1252 console; non-ASCII bytes raise UnicodeEncodeError.

Problem (WHY)

Per the repo's encoding contract (.github/instructions/encoding.instructions.md):

All source code files and CLI output strings must stay within printable ASCII (U+0020-U+007E). Windows cp1252 terminals raise UnicodeEncodeError: 'charmap' codec can't encode character for any character outside cp1252.

Two violations in install.ps1:

1. Em-dash (U+2014) at byte 29170 -- pre-existing comment: # need a retry — acceptable for an install/self-update operation.
2. Replacement characters (U+FFFD U+FFFD) at byte 33139 -- introduced by fix(install): write apm.cmd shim as ASCII (cmd.exe cannot parse UTF-16LE) #1522 in the comment I added describing what a UTF-16 cmd.exe parse failure looks like. I literally pasted the garbled-output illustration verbatim instead of describing it in ASCII.

Why this only surfaced now: #1522 fixed the apm.cmd shim, which previously crashed before reaching the self-update path. With the shim working, Test 5 can now exercise self-update end-to-end -- and immediately hits the cp1252 wall on the downloaded install.ps1.

Approach (WHAT)

Replace both non-ASCII sequences with their ASCII equivalents:

• — (em-dash) -> -- (ASCII digraph)
• ">��@" (replacement chars) -> plain ASCII prose describing the failure mode

install.ps1 now contains zero bytes above 0x7E (verified by hand-scan).

Validation evidence

• python3 -c "data = open('install.ps1','rb').read(); ..." reports no bytes > 127.
• 8/8 regression tests in tests/unit/install/test_windows_shim_template.py still pass.
• Full lint chain silent: ruff check, ruff format, pylint R0801.
• The actual Windows CI apm self-update test will run on this PR -- the only ground-truth verification.

Trade-offs

None. ASCII-equivalent prose is strictly required by the repo's encoding rule; this PR brings install.ps1 into compliance.

Refs #1522.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[Copilot]

Pull request overview

Removes two non-ASCII byte sequences from install.ps1 (an em-dash and replacement characters in comments) so that the v0.13.0 self-updater, which prints the downloaded script via a cp1252 Windows console, no longer raises UnicodeEncodeError. Brings the file into compliance with the repo's printable-ASCII encoding contract.

Changes:

• Replace em-dash with -- in the rollback-window comment at line 732.
• Replace ">��@" replacement chars with plain ASCII prose describing the UTF-16 cmd.exe failure mode at lines 805-806.

Show a summary per file

File	Description
install.ps1	Strips two non-ASCII byte sequences from comments to satisfy the printable-ASCII encoding rule.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0