fix(core): Resolve TypeScript strict mode and ES client API compatibility issues for v3.0.0

- Fix ES client v8+ API: use document/doc instead of body for index/update operations
- Add type assertions (as any) for ES client ILM, template, and search APIs
- Fix strict null checks with proper undefined handling (nullish coalescing)
- Fix MetricsCollector interface to match required method signatures
- Fix Logger.error signature compatibility in plugins
- Resolve TermsQuery type index signature conflict
- Remove sourceMap from tsconfig (handled by tsbuild with inlineSourceMap)

ts/examples/transactions/transaction-example.ts

@@ -11,6 +11,7 @@ import {
   createTransactionManager,
   type TransactionCallbacks,
   type ConflictInfo,
+  type ConflictResolutionStrategy,
 } from '../../index.js';
 
 interface BankAccount {
@@ -270,7 +271,7 @@ async function main() {
   let conflictsDetected = 0;
 
   const callbacks: TransactionCallbacks = {
-    onConflict: async (conflict: ConflictInfo) => {
+    onConflict: async (conflict: ConflictInfo): Promise<ConflictResolutionStrategy> => {
       conflictsDetected++;
       console.log(`  ⚠ Conflict detected on ${conflict.operation.index}/${conflict.operation.id}`);
       return 'retry'; // Automatically retry