[evandhoffman]

Summary

This PR automates the App Store screenshot upload. It is item 2 of #132, the screenshot part.

• ci/appstore-screenshots.txt: the approved set, in store order. This file is the one place where the set is chosen.
• appstore-screenshots.yml: a dispatch-only workflow on the Linux runner. Inputs: version, run_id (optional) and dry_run (default true).
  • It takes the screenshots artifact of the newest successful TestFlight run on v<version>, or of the run you name.
  • It checks the set, and it uploads only when dry_run=false.
• scripts/upload_appstore_screenshots.py: ported from StationCast, with 60 new tests.
  • It refuses before any write when:
    • a name has no file;
    • an image's size has no App Store slot;
    • an image has an alpha channel;
    • the images span more than one display type;
    • the set has more than 10 images;
    • the version is missing or cannot be edited;
    • the locale has no localization.
  • Otherwise it replaces the 6.9-inch set in manifest order, waits until Apple marks each image delivered, then sets the order.
• release-testflight.yml: it now uploads the screenshots artifact too, so each release tag's run holds images that show that release's version number.
• Settings screenshots: they hide the simulator-only "Testing" section, which the shipped app does not have. SettingsView.showsTestingTools is read only in simulator builds.
• httpx logging: all three App Store Connect scripts keep httpx and httpcore logging at WARNING, so the pre-signed upload URLs stay out of the logs.

Verification

• actionlint: no findings.
• ruff, mypy --strict and pytest -rs: 202 passed, 0 skipped.
• ci/lint_swift.sh: 0 violations.
• pre-commit run --all-files: all hooks pass.
• Compile-only build-for-testing: 0 errors and 0 Swift warnings.
• The real images:
  • The 18 images from run 38284188110 are all 1320 × 2868 with no alpha. The plan builds in the approved order.
  • The 18 older images are 1206 × 2622 with alpha, and they are refused.
• Not run: the workflow and any App Store Connect call. The first live check is a dry run after the merge.

Release

skip-release. CI and tooling only. The app change exists only in simulator builds.