Resolve open product questions for the client-apps release

[ahmetabdullahgultekin]

Why: §13 Open Questions block release decisions and need a product sign-off.

Done when answered/recorded:

1. Beta tester pool: Marmara CSE only or open? (recommend: Android open beta, Desktop public).
2. Privacy policy URL ownership: who signs off fivucsas.com/privacy TR+EN content?
3. Windows cert budget: approve ~$200 Sectigo OV, or ship v6 unsigned with SmartScreen docs?
4. APK v5.x -> AAB: cut a final frozen v5.2 APK sideload before the v6.0 AAB? (recommend yes).
   (Question 5 — iOS/macOS — already resolved: DROPPED 2026-04-26.)

source: plans/CLIENT_APPS_PARITY.md:335

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Migrated from plans/CLIENT_APPS_PARITY.md (git history retains the original).