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>

src/transaction/TransactionManager.ts

@@ -0,0 +1,189 @@
+/**
+ * Transaction Manager
+ *
+ * Manages transaction execution across the system.
+ * Provides high-level API for executing atomic operations.
+ *
+ * Usage:
+ * ```typescript
+ * const txManager = new TransactionManager()
+ *
+ * const result = await txManager.executeTransaction(async (tx) => {
+ *   tx.addOperation(operation1)
+ *   tx.addOperation(operation2)
+ *   return someValue
+ * })
+ * ```
+ */
+
+import { Transaction } from './Transaction.js'
+import {
+  TransactionFunction,
+  TransactionResult,
+  TransactionOptions
+} from './types.js'
+import { TransactionError } from './errors.js'
+import { prodLog } from '../utils/logger.js'
+
+/**
+ * Transaction Manager Statistics
+ */
+export interface TransactionStats {
+  totalTransactions: number
+  successfulTransactions: number
+  failedTransactions: number
+  rolledBackTransactions: number
+  averageExecutionTimeMs: number
+  averageOperationsPerTransaction: number
+}
+
+/**
+ * Transaction Manager
+ */
+export class TransactionManager {
+  private stats: TransactionStats = {
+    totalTransactions: 0,
+    successfulTransactions: 0,
+    failedTransactions: 0,
+    rolledBackTransactions: 0,
+    averageExecutionTimeMs: 0,
+    averageOperationsPerTransaction: 0
+  }
+
+  private totalExecutionTime = 0
+  private totalOperations = 0
+
+  /**
+   * Execute a function within a transaction
+   * All operations succeed atomically or all rollback
+   *
+   * @param fn Function that builds and executes transaction
+   * @param options Transaction execution options
+   * @returns Result from user function
+   * @throws TransactionError if transaction fails
+   */
+  async executeTransaction<T>(
+    fn: TransactionFunction<T>,
+    options?: TransactionOptions
+  ): Promise<T> {
+    const transaction = new Transaction(options)
+
+    this.stats.totalTransactions++
+
+    try {
+      // Execute user function (builds operations list)
+      const result = await fn(transaction)
+
+      // Execute all operations atomically
+      await transaction.execute()
+
+      // Update statistics
+      this.stats.successfulTransactions++
+      this.updateStats(transaction)
+
+      return result
+
+    } catch (error) {
+      // Transaction failed and rolled back
+      this.stats.failedTransactions++
+
+      if (transaction.getState() === 'rolled_back') {
+        this.stats.rolledBackTransactions++
+      }
+
+      this.updateStats(transaction)
+
+      // Re-throw with context
+      if (error instanceof TransactionError) {
+        throw error
+      } else {
+        throw new TransactionError(
+          `Transaction failed: ${(error as Error).message}`,
+          { cause: error }
+        )
+      }
+    }
+  }
+
+  /**
+   * Execute a transaction and return detailed result
+   */
+  async executeTransactionWithResult<T>(
+    fn: TransactionFunction<T>,
+    options?: TransactionOptions
+  ): Promise<TransactionResult<T>> {
+    const startTime = Date.now()
+    const transaction = new Transaction(options)
+
+    try {
+      const value = await fn(transaction)
+      await transaction.execute()
+
+      const executionTimeMs = Date.now() - startTime
+
+      return {
+        value,
+        operationCount: transaction.getOperationCount(),
+        executionTimeMs
+      }
+
+    } catch (error) {
+      // Transaction failed
+      throw error
+    }
+  }
+
+  /**
+   * Get transaction statistics
+   */
+  getStats(): Readonly<TransactionStats> {
+    return { ...this.stats }
+  }
+
+  /**
+   * Reset transaction statistics
+   */
+  resetStats(): void {
+    this.stats = {
+      totalTransactions: 0,
+      successfulTransactions: 0,
+      failedTransactions: 0,
+      rolledBackTransactions: 0,
+      averageExecutionTimeMs: 0,
+      averageOperationsPerTransaction: 0
+    }
+    this.totalExecutionTime = 0
+    this.totalOperations = 0
+  }
+
+  /**
+   * Update running statistics
+   */
+  private updateStats(transaction: Transaction): void {
+    const executionTime = transaction.getExecutionTimeMs()
+    const operationCount = transaction.getOperationCount()
+
+    if (executionTime !== undefined) {
+      this.totalExecutionTime += executionTime
+      this.stats.averageExecutionTimeMs =
+        this.totalExecutionTime / this.stats.totalTransactions
+    }
+
+    this.totalOperations += operationCount
+    this.stats.averageOperationsPerTransaction =
+      this.totalOperations / this.stats.totalTransactions
+  }
+
+  /**
+   * Log current statistics
+   */
+  logStats(): void {
+    prodLog.info('[TransactionManager] Statistics:')
+    prodLog.info(`  Total: ${this.stats.totalTransactions}`)
+    prodLog.info(`  Successful: ${this.stats.successfulTransactions}`)
+    prodLog.info(`  Failed: ${this.stats.failedTransactions}`)
+    prodLog.info(`  Rolled back: ${this.stats.rolledBackTransactions}`)
+    prodLog.info(`  Avg execution time: ${this.stats.averageExecutionTimeMs.toFixed(2)}ms`)
+    prodLog.info(`  Avg operations/tx: ${this.stats.averageOperationsPerTransaction.toFixed(2)}`)
+  }
+}