Enable Time-In-Range calculation in TherapyMetricsCard

[jwoglom]

Summary

This PR enables the Time-In-Range (TIR) metric calculation in the TherapyMetricsCard component by implementing CGM history log reading and processing.

Key Changes

• Uncommented and refactored TIR calculation logic: Activated the previously commented-out code that calculates 24-hour Time-In-Range (70–180 mg/dL) from CGM history logs
• Simplified CGM data extraction: Replaced inline type checking with new helper functions CgmReadingHistoryLogs and toCgmDataPoint() for cleaner code
• Removed unused imports and code: Cleaned up imports for unused history log types and removed incomplete COB (Carbs On Board) calculation code that was marked as "NOT READY YET"
• Updated function documentation: Clarified that TherapyMetricsCardFromDataStore now reads IOB from DataStore and computes 24h TIR from CGM history
• Removed unused parameters: Eliminated showCOB and showTIR boolean parameters that were not being utilized

Implementation Details

• TIR is calculated by querying the last 288 CGM readings (~24 hours at 5-minute intervals)
• Valid glucose readings are extracted using the new toCgmDataPoint() helper function
• The percentage of readings within the 70–180 mg/dL range is computed and passed to the TherapyMetricsCard
• COB calculation remains disabled pending further development

https://claude.ai/code/session_011pBoh7DKJz78xNjzaACouH