[fadkeprasad]

What this PR does

Power saving stretches the periodic history timer to 45 minutes, or 60 minutes with Low refresh, but Apple's live strap events still reach requestSync(.strap) through a 90-second floor. Repeated events can bypass the selected saving cadence.

Pass the active saving interval into BackfillPolicy.shouldRun on both platforms. Periodic and strap-event attempts use the greater of that interval and their existing empty-history backoff. Synthetic events every 90 seconds over two hours now permit starts at 3600 and 7200 seconds with Low refresh, rather than all 80 attempts.

• With saving inactive, the existing event floor remains unchanged.
• Low-battery saving still requires the strap to be at/below its threshold and not reported charging. Low refresh applies at any charge.
• Manual sync, reconnect/foreground recovery, the first sync and bounded backlog continuations retain their policies.
• No new BLE command, payload, polling, stream change or storage change.
• Android has no current production STRAP caller; its policy twin stays aligned. Both platforms also protect against a previously armed periodic timer firing before a newly active saving interval.

Refs #1430.

Type of change

• Bug fix

How it was tested

• macOS app build and 34 focused StrandTests pass: BackfillPolicyTests, LowRefreshCadenceTests and Whoop5BatteryBackfillThrottleTests.
• NOOPiOS generic-device build passes, including embedded watch targets. Signing disabled.
• Android production/test Kotlin compile and 34 focused JVM tests pass: BackfillPolicyTest, LowRefreshCadenceTest and ConnectionPriorityTest. Initial run used --no-build-cache --rerun-tasks.
• Compiled production Swift oracle covers 5,760 decisions across triggers, time boundaries, first sync, empty streaks, clock trust and saving floors. Both platform tests pin the same SHA-256. A negative control restoring the old gate changes that digest and reproduces the bypass.
• Doc-comment lint, diff-scoped i18n audit, parity ratchet against upstream main and git diff --check pass.
• No package sources changed; package suites and the full app/Android suites were not run.

Hardware validation

Draft pending a charged WHOOP 5.0 run. Existing local strap logs show frequent event-triggered history attempts, but predate the saving-setting change and do not prove an energy benefit. This patch has not been installed on a phone or validated on a physical strap. No battery-life improvement or sole cause of an individual discharge is claimed. Raw health data and private logs are not included.

Checklist

• Swift/Kotlin policy parity checked with a compiled oracle
• Focused Android and Apple tests passed
• Apple app targets compiled
• No UI or protocol literals changed
• No generated output, secrets or private captures committed