feat: Add Dynamic ISF data accumulation progress indicator

[Sjoerd-Bo3]

Summary

• Adds visual progress indicator for Dynamic ISF data accumulation
• Shows users how many days of TDD data have been collected (requires 7 days)
• Improves transparency during the warmup period
• Resolves Add Countdown for Dynamic ISF "Warmup" nightscout/Trio#560

Description

This PR implements a progress tracking system for Dynamic ISF to address user confusion about when the feature becomes active. The new progress indicator clearly shows:

• Current vs required data points
• Progress bar visualization
• Days of data collected
• Clear messaging about the 7-day requirement

Key Features

1. Progress View Component: Clean, reusable SwiftUI component with:

   • Progress bar with gradient fill
   • Percentage and day count display
   • Informative text about data requirements

2. Data Tracking:

   • Fetches actual TDD record count from Core Data
   • Updates automatically as new data is recorded
   • Handles edge cases (no data, partial data)

3. UI Integration:

   • Displays prominently at top of Dynamic Settings when data is insufficient
   • Automatically hides when 7 days of data are available
   • Maintains consistent styling with rest of the app

Test plan

• Enable Dynamic ISF on a fresh install or with <7 days of data
• Verify progress indicator appears at top of Dynamic Settings
• Check that progress bar and counts update as days pass
• Confirm indicator disappears after 7 days of TDD data
• Test with various data scenarios (0 days, partial days, full 7 days)
• Verify no impact on existing Dynamic ISF functionality

Screenshots

Progress Indicator	In Settings View
!Progress View	!Settings Integration