feat: add orderBy sorting and fix timestamp queries

Add production-scale sorting support with orderBy/order parameters:
- Sort by any field including createdAt, updatedAt, timestamps
- Works in both metadata-only and vector+metadata query paths
- O(k) memory complexity where k = filtered results

Fix timestamp sorting precision issue:
- Load actual timestamp values from entity metadata for sorting
- Avoids 1-minute bucketing precision loss
- Maintains bucketing for efficient range queries

Fix range query operators:
- Normalize min/max bounds before comparison with bucketed index
- Ensures gte, lte, gt, lt work correctly with timestamps

Standardize operator syntax:
- Canonical: eq, ne, gt, gte, lt, lte, in, between, contains, exists
- Deprecate: is, isNot, greaterEqual, lessEqual (remove in v5.0.0)
- Maintain backward compatibility with aliases

Test results: All sorting and range query tests pass, no regressions

src/types/brainy.types.ts

@@ -180,7 +180,11 @@ export interface FindParams<T = any> {
   limit?: number             // Max results (default: 10)
   offset?: number            // Skip N results
   cursor?: string            // Cursor-based pagination
-  
+
+  // Sorting (v4.5.4)
+  orderBy?: string           // Field to sort by (e.g., 'createdAt', 'title', 'metadata.priority')
+  order?: 'asc' | 'desc'     // Sort direction: 'asc' (default) or 'desc'
+
   // Advanced options
   mode?: SearchMode          // Search strategy
   explain?: boolean          // Return scoring explanation