Feat: Major UI re-haul - #35

Summary

This started as porting the low-level ring protocol from the Android app, but turned into a much larger redesign of how vitals, activity, and sleep are shown across the app.

Vitals page

• Rebuilt every vital as a consistent card with a big current value, a "normal / elevated / high" status badge, and how it's changed versus earlier
• Added a shared threshold engine so every metric decides its status and color in one place, using conservative medical reference ranges (nothing is presented as a diagnosis)
• Ring-estimated metrics (blood pressure, blood sugar, fatigue) are clearly tagged as "estimated" so they aren't mistaken for real sensor readings
• You can now turn individual vital tiles on or off, and smooth out busy charts, without affecting the stored data

Metric detail pages (new)

• Tap any vital to open a full detail screen with Today / Week / Month period switching
• Full-axis chart with colored reference zones, latest / average / min / max stat tiles, a reference-zone legend, and a plain-language "what this means" explainer
• Blood pressure shows systolic and diastolic together on one chart

Today page

• Redesigned all the tiles: a "momentum" summary up top, activity rings, sleep score, and quick-glance heart rate, blood oxygen, HRV, and temperature tiles

Activity page

• Reworked the activity widget with combined steps / distance / calories rings
• New Activity Trends screen showing steps, distance, and calories over Week / Month / Year against your daily goals

Sleep page

• Cleaner sleep architecture graph with clearer stage bands and stage breakdown tiles

New settings

• Calibration screen: enter a cuff or lab reading to correct the ring's blood pressure and blood sugar estimates
  Physiology screen: athlete mode, altitude, health context (beta-blockers, lung conditions), and glucose units, which adjust what's considered normal for you

Under the hood

• Ported the low-level ring protocol from the Android app (better decoding, ring configuration, connection reliability, and calibration)
• New threshold engine, chart sample model, and source-quality resolver, all backed by unit tests

Related issues

Type of change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 📟 New / improved wearable support (BLE driver layer)
• 🤖 Coach / LLM change (tools, prompts, orchestration)
• 🎨 UI / DesignSystem change
• 🧹 Refactor / chore (no behavior change)
• 📝 Docs only
• ⚠️ Breaking change (existing data, settings, or APIs change)

How was this tested?

Tested with Colmi R11 on iPhone 16 Pro.

• Added / updated unit tests (PulseLoopTests)
• Ran the test suite locally (⌘U in Xcode)
• Tested on a physical device with a real ring — model: Colmi R11
• Tested with demo data (-seedDemo YES, no hardware)
• N/A (docs / non-code change)

Privacy & data

• This change does not send health data off-device without explicit user action.
• No secrets, API keys, or personal data are committed.
• N/A

Screenshots / recordings

Checklist

• My code follows the project's style (SwiftLint passes).
• I ran the tests and they pass.
• I updated docs / README where relevant.
• I read the Contributing guide.