Align screenshot workflow choices

[cbusillo]

Summary

• expose the existing iphone65 approved screenshot set in the manual upload workflow
• assert exact membership parity between workflow choices and script-supported sets
• reject duplicate workflow choices and preserve the safe macos first choice
• replace ambiguous per-option substring assertions with a fail-loud scoped helper

Evidence

• the new parity test was observed failing before the workflow fix because iphone65 was missing
• 145 targeted screenshot/workflow tests passed after the fix
• all 10 routine Python lane files passed
• actionlint .github/workflows/upload-app-store-screenshots.yml passed
• scripts/commit-gate.sh passed, including all 889 Swift tests
• Opus final review approved
• Gemini final route was invoked but returned no usable review text

Refs #579