fix(install.ps1): use string concatenation instead of interpolation w…

[Nan0pk]

…/ parens

PS 5.1 still failing on line 381 even after the previous fix:

At C:\Users\TTT\install.ps1:381 char:51

• Write-Host "`r $Pct% ($WrittenMB MB / $TotalMB MB) @ ...

•                                        ~~
  

Unexpected token 'MB' in expression or statement.

Root cause: PowerShell 5.1's tokenizer treats the opening paren inside a double-quoted string followed by a variable as a potential subexpression start, and when the contents don't form a valid subexpression, the parser falls over. The pattern ($Varname Text) is the specific trigger.

The previous fix used native string interpolation with the suspect pattern still embedded:
Write-Host "`r $Pct% ($WrittenMB MB / $TotalMB MB) @ $Rate MB/s" -NoNewline

This commit replaces it with explicit string concatenation — no parens inside the string at all:

$ProgressLine = "`r " + $Pct + "% " + $WrittenMB + " MB / " + $TotalMB + " MB @ " + $Rate + " MB/s"
Write-Host $ProgressLine -NoNewline

Verified:

• PowerShell 7 parser: PARSE OK (0 errors).
• Static scan for suspect '(' patterns in string literals: 0 found.
• install.ps1 -Help still runs cleanly.

Lesson learned: stop hand-writing PowerShell string interpolation that contains parentheses. Use concatenation, or pre-compute variables and reference them with simple $Varname interpolation (no parens).

What Does This Change?

A clear description of what this PR changes and why.

Motivation

Why is this change needed? Link to the issue it resolves (e.g., Closes #123)
or explain the problem it solves.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that changes existing behavior)
• Refactor (no functional change)
• Documentation update
• CI / build system change
• Kernel config change
• Policy / defaults change

Testing

• cargo test --workspace passes
• cargo clippy --workspace --all-targets -- -D warnings passes
• cargo fmt --all -- --check passes
• pwsh ./tools/validate-repo.ps1 passes
• python3 tools/validate-evidence.py passes (Dragnet gate)
• New or updated tests added for this change

Evidence (Dragnet)

• If this PR sets any milestone criterion verified = true, it commits the
  acceptance transcript and python3 tools/dragnet.py --observe is GREEN
  with zero pending ledger rows for that milestone. (See docs/dragnet-protocol.md.)

Documentation

Documentation updates are required for changes to behavior, defaults,
policy, boot/update flow, kernel fragments, recipes, or service behavior.

• No documentation update needed (explain why below)
• docs/IMPLEMENTATION_STATUS.md updated
• Relevant docs updated (list which ones):

  • ---

• ADR added or amended (if this changes architectural direction)

If no doc update is needed, explain why:

---

Checklist

• I have read CONTRIBUTING.md
• My changes follow the project's design rules (modern defaults,
  one adaptive policy owner, explainable behavior)
• No legacy defaults were introduced without justification
• No guardrails were weakened
• If this changes privileged actions, SECURITY.md and relevant
  ADRs are updated