Optimize Battery & Network Usage

Background: Native [platform] app, [SwiftUI / Compose]. Concern:
[battery drain / excessive data usage / overheating]. Suspect activity:
[location, background sync, polling, video, frequent network, wake locks].

Use case: Reduce the app's energy and data footprint without breaking the
feature.

Implementation details:
- iOS: the Energy Log / Xcode energy gauges to attribute cost; batch and
  defer network, coalesce location updates, respect Low Power Mode, avoid
  needless wakeups and timers. Android: Battery Historian / energy
  profiler; use WorkManager with constraints, avoid wake locks, batch
  network with appropriate scheduling, respect Doze/Battery Saver.
- Reduce network: batching, caching (Section 5.3), compression,
  pagination, and not polling when push/events suffice
- Back off work on low battery / metered connections
- Confirm the improvement with the energy/network tools

Deliverable: The attributed sources of drain/usage, the per-platform
reductions (batching, deferral, backoff, caching), how to respect Low
Power / Doze / metered states, and how to verify the savings.