feat(intelligence): complete Phase 2-3 migration to Rust

Phase 2 - Core Engines:
- Heartbeat Engine: Periodic proactive checks with quiet hours support
- Context Compactor: Token estimation and message summarization
  - CJK character handling (1.5 tokens per char)
  - Rule-based summary generation

Phase 3 - Advanced Features:
- Reflection Engine: Pattern analysis and improvement suggestions
- Agent Identity: SOUL.md/AGENTS.md/USER.md management
  - Proposal-based changes (requires user approval)
  - Snapshot history for rollback

All modules include:
- Tauri commands for frontend integration
- Unit tests
- Re-exported types via mod.rs

Reference: docs/plans/INTELLIGENCE-LAYER-MIGRATION.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src-tauri/src/intelligence/mod.rs

@@ -0,0 +1,52 @@
+//! Intelligence Layer - Migrated from frontend lib/
+//!
+//! This module contains the intelligence components that were previously
+//! implemented in TypeScript/JavaScript in the frontend.
+//!
+//! ## Modules
+//!
+//! - `heartbeat` - Periodic proactive checks with quiet hours support
+//! - `compactor` - Context compaction for infinite-length conversations
+//! - `reflection` - Agent self-improvement through conversation analysis
+//! - `identity` - Agent identity file management (SOUL.md, AGENTS.md, USER.md)
+//!
+//! ## Migration Status
+//!
+//! | Component | Status | Notes |
+//! |-----------|--------|-------|
+//! | Heartbeat Engine | ✅ Phase 2 | Complete |
+//! | Context Compactor | ✅ Phase 2 | Complete |
+//! | Reflection Engine | ✅ Phase 3 | Complete |
+//! | Agent Identity | ✅ Phase 3 | Complete |
+//! | Agent Swarm | 🚧 Phase 3 | TODO |
+//! | Vector Memory | 📋 Phase 4 | Planned |
+//!
+//! Reference: docs/plans/INTELLIGENCE-LAYER-MIGRATION.md
+
+pub mod heartbeat;
+pub mod compactor;
+pub mod reflection;
+pub mod identity;
+
+// Re-export main types for convenience
+pub use heartbeat::{
+    HeartbeatConfig, HeartbeatEngine, HeartbeatEngineState,
+    HeartbeatAlert, HeartbeatResult, HeartbeatStatus,
+    Urgency, NotifyChannel, ProactivityLevel,
+};
+pub use compactor::{
+    CompactionConfig, ContextCompactor, CompactableMessage,
+    CompactionResult, CompactionCheck, CompactionUrgency,
+    estimate_tokens, estimate_messages_tokens,
+};
+pub use reflection::{
+    ReflectionConfig, ReflectionEngine, ReflectionEngineState,
+    ReflectionResult, ReflectionState, ReflectionResult as ReflectionOutput,
+    PatternObservation, ImprovementSuggestion, IdentityChangeProposal as ReflectionIdentityChangeProposal,
+    Sentiment, Priority, MemoryEntryForAnalysis,
+};
+pub use identity::{
+    AgentIdentityManager, IdentityManagerState,
+    IdentityFiles, IdentityChangeProposal, IdentitySnapshot,
+    IdentityFile, ProposalStatus,
+};