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>

PulseHealth/PulseHealth.entitlements

@@ -6,5 +6,9 @@
 	<true/>
 	<key>com.apple.developer.healthkit.background-delivery</key>
 	<true/>
+	<key>keychain-access-groups</key>
+	<array>
+		<string>$(AppIdentifierPrefix)com.daniil.pulsehealth.shared</string>
+	</array>
 </dict>
 </plist>