Add relevant iOS CI

[ctbeiser]

Summary

• add pull-request, main, and manually dispatched iOS CI
• run deterministic formatting and strict SwiftLint for the app and share extension
• build the full unsigned simulator scheme
• replace the stale orion lint scope with the real EchoShareExtension

Why

Echo had GitHub Actions enabled but no workflow. Its lint configuration also omitted the shipped share extension, so adding CI without correcting that scope would have produced a misleading green check.

Validation

• Apple Bash 3.2 syntax for all scripts and hooks
• actionlint .github/workflows/ios-ci.yml
• autofix idempotence and strict SwiftLint across all six Swift files
• target-specific lint scope: five app files and one extension file
• scripts/verify-full.sh using the unsigned Verify Full simulator scheme
• git diff --check