Maintain the App Over Time

Background: Native [iOS / Android / both] app that's live and needs to
stay healthy as the platforms evolve. Current state: [dependency
freshness, min OS versions, known tech debt]. 

Use case: Help me build a maintenance plan so the app doesn't rot between
feature pushes.

Implementation details:
- The annual platform cadence: new iOS/Android versions, new required
  device sizes, SDK target-level requirements the stores will mandate by
  deadline
- A dependency-upkeep routine: updating libraries, watching for
  deprecations and security advisories, and the risk of falling behind
- Tech-debt management: tracking it, and budgeting a slice of each release
  to pay it down before it compounds
- Deprecation handling: APIs being removed, raising the minimum OS, and
  sunsetting old app versions (minimum-version gating from 11.6)
- Keeping CI, signing certs, and store requirements from silently expiring

Deliverable: A maintenance plan with the platform-update calendar, a
dependency/deprecation review routine, a tech-debt budgeting approach,
and the recurring operational checks (cert/CI/store) that prevent
surprises.