feat: add v5.8.0 features - transactions, pagination, and comprehensive docs

**Transaction System (TIER 1.2)**
- Atomic operations with automatic rollback
- 36 unit tests + 35 integration tests passing
- Full documentation in docs/transactions.md

**Duplicate Check Optimization (TIER 1.4)**
- Optimized from O(n) to O(log n) using GraphAdjacencyIndex
- Uses LSM-tree for efficient lookups
- Tests verify performance improvements

**GraphIndex Pagination (TIER 1.5)**
- Production-scale pagination for high-degree nodes
- Backward compatible API
- 18 pagination tests passing

**Comprehensive Filter Documentation (TIER 1.6)**
- Complete operator reference (15 operators)
- Compound filters (anyOf, allOf, nested logic)
- Common query patterns and troubleshooting guide
- 642 lines of new documentation

**README Updates**
- Added Filter & Query Syntax Guide to Essential Reading
- Added Transactions to Core Concepts section

All changes tested and production-ready for v5.8.0 release.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

README.md

@@ -631,16 +631,20 @@ This comprehensive guide includes:
    - Your primary resource for building with Brainy
    - Every method documented with working examples
 
-2. **[Natural Language Queries](docs/guides/natural-language.md)**
+2. **[Filter & Query Syntax Guide](docs/FIND_SYSTEM.md)**
+   - Complete reference for operators, compound filters, and optimization tips
+
+3. **[Natural Language Queries](docs/guides/natural-language.md)**
    - Master the `find()` method and Triple Intelligence queries
 
-3. **[v4.0.0 Migration Guide](docs/MIGRATION-V3-TO-V4.md)**
+4. **[v4.0.0 Migration Guide](docs/MIGRATION-V3-TO-V4.md)**
    - Upgrading from v3 (100% backward compatible)
 
 ### 🧠 Core Concepts & Architecture
 
 - **[Triple Intelligence Architecture](docs/architecture/triple-intelligence.md)** — How vector + graph + document work together
 - **[Noun-Verb Taxonomy](docs/architecture/noun-verb-taxonomy.md)** — The universal type system (42 nouns × 127 verbs)
+- **[Transactions](docs/transactions.md)** — Atomic operations with automatic rollback
 - **[Architecture Overview](docs/architecture/overview.md)** — System design and components
 - **[Data Storage Architecture](docs/architecture/data-storage-architecture.md)** — Type-aware indexing and HNSW