feat: iOS widgets + fix sleep showing yesterday's data

Widgets:
- HabitsProgressWidget (small/medium): progress ring, completed/total habits, tasks count
- HealthSummaryWidget (small/medium): readiness score, steps, sleep, heart rate
- Shared Keychain access group for app ↔ widget token sharing
- Widget data refreshes every 30 minutes

Sleep fix:
- Changed sleep window from "24 hours back" to "6 PM yesterday → now"
- Captures overnight sleep correctly without showing previous day's data
- Applied to both fetchSleepData (sync) and fetchSleepSegments (detail view)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PulseWidget/PulseWidget.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>keychain-access-groups</key>
+	<array>
+		<string>$(AppIdentifierPrefix)com.daniil.pulsehealth.shared</string>
+	</array>
+</dict>
+</plist>