fix(update): make TestExtractBinaryZip arch-aware

[Desperado]

Summary

TestExtractBinaryZip built its fixture archive with a hardcoded qmax-code-windows-amd64.exe member, but extractBinary (internal/update/update.go:280) looks up the host architecture via runtime.GOARCH. On any arm64 host the fixture and the lookup disagree, and the test fails with qmax-code-windows-arm64.exe not found in archive before the bytes-equal assertion is ever reached. The member name now uses runtime.GOARCH, mirroring the already-arch-aware sibling fixtures (TestExtractBinaryTarGz, TestApplySwapsBinary). Production code is untouched.

Why now

Filed as #204 after it surfaced while validating the v1.35.3 release on an arm64 machine. Every arm64 contributor currently sees a red go test ./... locally, and any future ARM CI runner (ubuntu-24.04-arm, macOS ARM) would break the release workflow's test gate — today's releases only pass because the runner happens to be amd64.

Risks / notes

• Behavior-neutral for amd64: the generated member name is identical there
• internal/update/update.go and the test file carry pre-existing gofmt drift on main (import ordering, const alignment); deliberately left out of this PR to keep the diff one line — CI gates on go vet, not gofmt
• Full package suite verified on both linux/arm64 and linux/amd64 under Go 1.25

Review instructions

Single-line diff in internal/update/update_test.go; compare against the sibling pattern at line 192 in the same file. Then it's just the Fixes footer below.

Closes #204

[qualitymaxapp]

QualityMax Review

Verdict: COMMENT · Confidence: evidence-backed scan

Files eligible: 1 · Files reviewed: 1 · Files with findings: 0 · Findings: 0 · Inline cards: 0

Priority findings

priority	location	finding
—	—	No blocking findings

Review gates

gate	status
AI diff review	completed · eligible 1, reviewed 1 · LLM · served gemini-3.1-flash-lite
SAST	completed · eligible 1, reviewed 1 · hybrid · served qwen3.7-plus
Overall review evidence	clean
Inline evidence	not needed

Important files

file	risk	note	next step
—	—	No findings	—

Review lifecycle

Use the inline cards to inspect evidence and suggested remediation. Re-run the QualityMax review after pushing a fix; unchanged cards are identified by their stable finding marker. Dismiss with a reason through the existing QualityMax/GitHub review feedback flow. 0 prior card(s) are stale/resolved on this head. @qmax Q&A is tracked separately.

Proof legend: VERIFIED independently judged patch · REPRODUCED verified finding · GROUNDED deterministic evidence · MODEL-ONLY model judgment.

QualityMax project results are available in the configured project.

_{Receipt · commit c55c373453deaf59c73b232e2921899f8569501c · run 2026-09-15T15:41:21+00:00 · model served qwen3.7-plus, gemini-3.1-flash-lite · model requested qwen3.7-plus, gemini-3.1-flash-lite · model review recorded — 631 model output tokens · model source repository ai_review_preferences.preferred_model · re-review 2 · proof counts {}}

[qualitymaxapp]

QualityMax Review — canonical overview updated; inline findings are attached to this review.

[qualitymaxapp]

⚠️ QualityMax Pipeline

Gate	Result
🔍 AI diff review	✅ Clean · gemini-3.1-flash-lite · completed · 1 eligible / 1 reviewed · gemini-3.1-flash-lite
🔍 SAST	completed · 1 eligible / 1 reviewed · qwen3.7-plus
🔍 Canonical PR review delivery	completed · 0 eligible / 0 reviewed · exact-head review #5212264309 and overview #5683239927 confirmed
🧪 Repo Tests	✅ 839/839 passed (go)

_{Powered by QualityMax — AI-Powered Test Automation}