Optimize App Startup / Cold Launch Time

Background: Native [platform] app, [SwiftUI / Compose]. Cold start feels
slow / measures [time if known]. What happens at launch: [describe—SDK
inits, network calls, db setup, auth check].

Use case: Reduce cold-launch time to the point the first screen appears
fast.

Implementation details:
- Measure launch phases first (iOS: the app launch Instruments template /
  signposts; Android: the reported startup metric / Macrobenchmark) to
  see where the time goes
- Defer non-critical work off the launch path: lazy-init SDKs, move work
  after first frame, avoid synchronous network/db on the main thread at
  startup
- iOS: minimize work in app init and the first view's body; watch static
  initializers. Android: audit Application.onCreate and any
  ContentProvider-based SDK auto-init; consider App Startup library.
- Show the first meaningful screen quickly, then fill in
- Avoid blocking on auth/remote config—render a sensible default

Deliverable: A prioritized list of launch-path costs to cut, the
deferral/lazy-init changes per platform, what must stay on the critical
path, and how to measure the before/after improvement.