Modernize the template: @Observable architecture, reusable toolkit, and CI/CD pipeline

[hoppsen]

Summary

Brings the template up to current conventions and adds a complete build & release pipeline.

App architecture

• Modern @Observable + async/await SwiftUI throughout — @State-owned view models,
  @Environment injection, // MARK:-organised view bodies. Files start at import (no headers).
• New Settings + Support screens rooted at SettingsView: language, contact-support mail
  (prefilled with version/build), legal links, share sheet, and a version footer.
• Home Screen quick-action bridge (AppDelegate/SceneDelegate → an @Observable service);
  the "Send Feedback" action opens the Support screen.

Reusable toolkit

• Shared Components/, Extensions/, Utilities/, Models/: mail & share representables,
  a Safari view, a loading indicator, a keyboard-height publisher, SwiftUI availability backports,
  alert/dialog types, a typed UserDefaults wrapper, a lightweight DI container, an os.Logger
  wrapper, and view modifiers.

Tooling & CI/CD

• fastlane lanes: build, test, deploy, calendar updateVersion, upload_metadata, plus
  match signing and setup / code-signing helpers, with staging and production schemes.
• GitHub Actions: linting, staging → TestFlight builds, a dispatchable release pipeline, and an
  App Store release monitor.
• Git hooks (pbxproj sort + per-file SwiftFormat/SwiftLint, commit-message & branch-name checks),
  SwiftFormat/SwiftLint config, and a CLAUDE.md contributor guide.

Notes

• Builds clean under Swift 6 (iOS 17+); SwiftFormat and SwiftLint pass.
• Org-specific values (team id, App Store Connect ids, signing repo, CI secrets)
  are placeholders marked # <- CHANGE — fill these in per project.