fix(config): --ios must not silently run an android project

[BenSheridanEdwards]

Summary

• resolveProject silently fell back to projects[0] when an explicit platform matched nothing — npx nativeproof --ios against an android-only config ran an Android suite, produced Android evidence, and reported success. It now fails loudly, listing the available projects (a typo'd --project already errored; a platform mismatch didn't).
• The CLI preflight resolved the project from flags only, while the runner honors PLATFORM/NATIVEPROOF_PROJECT env vars — so PLATFORM=ios nativeproof ensured the uiautomator2 driver and skipped the "iOS requires macOS" guard, then ran the iOS project (late, cryptic session failure). The preflight now uses the same flags-then-env selection (runSelection), so it always preflights the project the runner will actually execute.

Proof

• npm run check
  • Passed on fix/strict-platform-resolution.
• npm test
  • Passed: 156/156 (new tests: unmatched explicit platform throws listing available projects; runSelection env fallback and flag precedence).
• Generated project/device proof, or N/A:
  • Not applicable. Selection logic covered by unit tests; no device or generated-project surface changes (generated configs always contain the platform they were scaffolded for, so the loud-failure path only fires on genuine mismatches).
  • Screenshots: Not applicable; CLI/config resolution logic asserted in tests.

Risk

• Low-to-moderate: this is a deliberate behaviour change. Anyone relying on --ios silently running a non-iOS first project now gets an error naming the fix. A stray PLATFORM env var that the runner was already (silently) honouring now fails fast at preflight instead of steering the run unnoticed.

Notes

• Full device coverage not run: resolution happens before any device interaction.

PR Proof Law

• I followed .agents/DEFINITION_OF_DONE.md and .agents/skills/pr-inline-screenshot-proof/SKILL.md.
• Screenshots are committed and embedded inline with ![alt](...png?raw=1), or the proof section says Not applicable with the technical reason.
• The PR body has no bare screenshot links, local paths, relative paths, or proof placeholders.