Adaptive notification

[gloskull]

Motivation

• Reduce notification fatigue and battery usage by adapting delivery cadence to recent user activity instead of using a fixed frequency.
• Enforce per-notification-type throttling so noisy channels (e.g. messages) don’t overwhelm inactive users.

Description

• Added engagement tracking fields to the notification store: lastEngagedAt and lastNotificationSentAtByType and persisted them in storage (src/store/notificationStore.ts).
• Implemented helper actions recordEngagement(), getNotificationThrottleMinutes() (returns 5/30/180 minutes based on inactivity), and shouldThrottleNotification(type, now?) to enforce per-type throttling and update last-sent timestamps (src/store/notificationStore.ts).
• Wired behavior into notification handling: tapping a notification now calls recordEngagement(), and foreground notifications call shouldThrottleNotification() and are dropped (with a log) if they fall within the adaptive throttle window (src/utils/notificationHandlers.ts).
• Added unit test coverage for engagement-aware throttling and updated existing notification store tests to initialize the new fields (src/__tests__/store/notificationStore.test.ts, tests/store/notificationStore.test.ts).
• Documented the thresholds and behavior in README.md under "Adaptive Notification Throttling".

Testing

• Attempted to run the modified tests with npm test -- src/__tests__/store/notificationStore.test.ts src/__tests__/utils/notificationHandlers.test.ts tests/store/notificationStore.test.ts which failed because the jest binary is not available in the environment (error: sh: 1: jest: not found).
• Attempted to run tests with npx jest ... but fetching test runner failed due to registry access being blocked (npm error code E403), so tests could not be executed in this environment.
• No automated test failures were observed in-repo (tests were added/updated), but the execution attempts above were blocked by the environment and therefore test results are inconclusive.

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Closes #404

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[RUKAYAT-CODER]

kindly resolve conflict.