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/domain/kv/kv-store.ts

@@ -13,11 +13,7 @@
 
 import { ElasticsearchConnectionManager } from '../../core/connection/connection-manager.js';
 import { Logger, defaultLogger } from '../../core/observability/logger.js';
-import {
-  MetricsCollector,
-  defaultMetricsCollector,
-} from '../../core/observability/metrics.js';
-import { DocumentNotFoundError } from '../../core/errors/index.js';
+import { MetricsCollector, defaultMetricsCollector } from '../../core/observability/metrics.js';
 import type {
   KVStoreConfig,
   KVSetOptions,
@@ -27,7 +23,6 @@ import type {
   KVScanResult,
   KVOperationResult,
   KVStoreStats,
-  CacheStats,
   CacheEntry,
   KVDocument,
   KVBatchGetResult,
@@ -223,8 +218,8 @@ export class KVStore<T = unknown> {
       // Update cache
       if (this.config.enableCache && !options.skipCache) {
         this.cacheSet(key, value, {
-          seqNo: result._seq_no,
-          primaryTerm: result._primary_term,
+          seqNo: result._seq_no ?? 0,
+          primaryTerm: result._primary_term ?? 0,
         }, ttl);
       }
 
@@ -236,7 +231,7 @@ export class KVStore<T = unknown> {
 
       this.metrics.recordCounter('kv.set', 1, {
         index: this.config.index,
-        cached: !options.skipCache,
+        cached: options.skipCache ? 'no' : 'yes',
       });
       this.metrics.recordHistogram('kv.set.duration', duration);
 
@@ -244,8 +239,8 @@ export class KVStore<T = unknown> {
         success: true,
         exists: result.result === 'updated',
         version: {
-          seqNo: result._seq_no,
-          primaryTerm: result._primary_term,
+          seqNo: result._seq_no ?? 0,
+          primaryTerm: result._primary_term ?? 0,
         },
         expiresAt: expiresAt ?? undefined,
       };
@@ -281,7 +276,7 @@ export class KVStore<T = unknown> {
 
           this.metrics.recordCounter('kv.get', 1, {
             index: this.config.index,
-            cache_hit: true,
+            cache_hit: 'true',
           });
 
           return {
@@ -353,8 +348,8 @@ export class KVStore<T = unknown> {
           : undefined;
 
         this.cacheSet(key, value, {
-          seqNo: result._seq_no!,
-          primaryTerm: result._primary_term!,
+          seqNo: result._seq_no ?? 0,
+          primaryTerm: result._primary_term ?? 0,
         }, ttl);
       }
 
@@ -366,7 +361,7 @@ export class KVStore<T = unknown> {
 
       this.metrics.recordCounter('kv.get', 1, {
         index: this.config.index,
-        cache_hit: false,
+        cache_hit: 'false',
       });
       this.metrics.recordHistogram('kv.get.duration', duration);
 
@@ -376,8 +371,8 @@ export class KVStore<T = unknown> {
         exists: true,
         cacheHit: false,
         version: {
-          seqNo: result._seq_no!,
-          primaryTerm: result._primary_term!,
+          seqNo: result._seq_no ?? 0,
+          primaryTerm: result._primary_term ?? 0,
         },
         expiresAt: doc.expiresAt ? new Date(doc.expiresAt) : undefined,
       };
@@ -732,10 +727,8 @@ export class KVStore<T = unknown> {
         }
       }
 
-      const nextCursor =
-        result.hits.hits.length > 0
-          ? result.hits.hits[result.hits.hits.length - 1].sort?.[0] as string
-          : undefined;
+      const lastHit = result.hits.hits[result.hits.hits.length - 1];
+      const nextCursor = lastHit?.sort?.[0] as string | undefined;
 
       this.metrics.recordCounter('kv.scan', 1, {
         index: this.config.index,