Added #

• SynheartSession main class with live and mock constructors.
• LiveSessionEngine — Dart-side session engine that consumes real HR data from synheart_wear (via SynheartWear.streamHR() or BleHrmProvider.onHeartRate) and behavioral signals from synheart_behavior (SynheartBehavior.getCurrentStats()).
• _HrRingBuffer — circular buffer for time-windowed HR sample storage with real SDNN/RMSSD computation from actual RR intervals.
• SynheartSession constructor accepts optional wear, bleHrm, and behavior parameters for live mode.
• SynheartSession.mock() constructor for local development and testing (sinusoidal HR generation).
• MockSessionEngine with MockHrGenerator for deterministic mock HR data.
• BehaviorSnapshot class and BehaviorProvider abstract class for pluggable behavioral signal sources (pull-based).
• MockBehaviorProvider — returns stable mid-range behavioral values for testing.
• SessionFrame and SessionSummary carry an optional behavior field (Map<String, dynamic>?).
• Dart type definitions matching session.proto schema (SessionConfig, SessionEvent, SessionStatus).
• Platform channel bridge (MethodChannel + EventChannel) for iOS watch relay.
• iOS SynheartSessionPlugin.swift — watch relay + getWatchStatus only (via WCSession).
• Android SynheartSessionPlugin.kt — minimal no-op stub for plugin registration.
• synheart_wear and synheart_behavior as dependencies.
• Type-safe session events: SessionStarted, SessionFrame, BiosignalFrame, SessionSummary, SessionError.
• Configurable ComputeProfile (window size, emit interval).
• Tests: mock_session_test.dart, session_test.dart, behavior_provider_test.dart, live_session_engine_test.dart, types_test.dart.