fix(storage): resolve persistence restart bug across all storage adapters

Critical bug fix that restores data persistence after application restart for all storage adapters (GCS, S3, OPFS, FileSystem).

**Root Cause:**
Storage adapters were loading entity counts from _system/counts.json but not returning totalCount in pagination methods, causing rebuildIndexesIfNeeded() to see undefined and incorrectly assume no data existed.

**Changes:**
- GCS Storage: Return totalCount in getNodesWithPagination() and getVerbsWithPagination()
- S3 Storage: Call initializeCounts() in init() and return totalCount in pagination methods
- OPFS Storage: Call initializeCounts() in init() to load pre-calculated counts
- BaseStorage: Add defensive validation to prevent future adapters from missing totalCount

**Impact:**
- Production deployments now work correctly (Cloud Run, AWS, Kubernetes)
- Data persists correctly across container restarts
- Serverless scale-to-zero deployments now functional
- All storage adapters use O(1) pre-calculated counts (scales to millions of entities)

**Testing:**
- Build passes with no TypeScript errors
- All existing tests pass
- Defensive validation ensures future storage adapters won't have this bug

Fixes critical production issue affecting all persistent storage deployments.

src/storage/adapters/s3CompatibleStorage.ts

@@ -346,7 +346,10 @@ export class S3CompatibleStorage extends BaseStorage {
       
       // Auto-cleanup legacy /index folder on initialization
       await this.cleanupLegacyIndexFolder()
-      
+
+      // Initialize counts from storage
+      await this.initializeCounts()
+
       this.isInitialized = true
       this.logger.info(`Initialized ${this.serviceType} storage with bucket ${this.bucketName}`)
     } catch (error) {
@@ -1843,6 +1846,7 @@ export class S3CompatibleStorage extends BaseStorage {
     
     return {
       items: filteredGraphVerbs,
+      totalCount: this.totalVerbCount,  // Use pre-calculated count from init()
       hasMore: result.hasMore,
       nextCursor: result.nextCursor
     }
@@ -3367,21 +3371,9 @@ export class S3CompatibleStorage extends BaseStorage {
       }
     }
     
-    // Calculate total count efficiently
-    // For the first page (no cursor), we can estimate total count
-    let totalCount: number | undefined
-    if (!cursor) {
-      try {
-        totalCount = await this.estimateTotalNounCount()
-      } catch (error) {
-        this.logger.warn('Failed to estimate total noun count:', error)
-        // totalCount remains undefined
-      }
-    }
-
     return {
       items: filteredNodes,
-      totalCount,
+      totalCount: this.totalNounCount,  // Use pre-calculated count from init()
       hasMore: result.hasMore,
       nextCursor: result.nextCursor
     }