fix: Improve filter translation logic and documentation

- Fix multiple operators on same field (always AND them together)
- Remove $not from type documentation
- Clarify range operators use $gte/$lte not $between
- All 290 tests passing

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/foundation/core/src/repository.ts

@@ -109,9 +109,13 @@ export class ObjectRepository {
             if (value === null || value === undefined) {
                 nodes.push([field, '=', value]);
             } else if (typeof value === 'object' && !Array.isArray(value) && !(value instanceof Date)) {
-                // Explicit operators
-                for (const [op, opValue] of Object.entries(value)) {
-                    if (nodes.length > 0 && nodes[nodes.length - 1] !== 'and') {
+                // Explicit operators - multiple operators on same field are AND-ed together
+                const entries = Object.entries(value);
+                for (let i = 0; i < entries.length; i++) {
+                    const [op, opValue] = entries[i];
+                    
+                    // Add 'and' before each operator (except the very first node)
+                    if (nodes.length > 0 || i > 0) {
                         nodes.push('and');
                     }
 

packages/foundation/types/src/query.ts

@@ -14,11 +14,13 @@ import type { FilterCondition } from '@objectstack/spec';
  * Supports MongoDB/Prisma-style object-based syntax:
  * - Implicit equality: { field: value }
  * - Explicit operators: { field: { $eq: value, $gt: 10 } }
- * - Logical operators: { $and: [...], $or: [...], $not: {...} }
+ * - Logical operators: { $and: [...], $or: [...] }
  * - String operators: { name: { $contains: "text" } }
- * - Range operators: { age: { $between: [18, 65] } }
+ * - Range operators: { age: { $gte: 18, $lte: 65 } }
  * - Set operators: { status: { $in: ["active", "pending"] } }
  * - Null checks: { field: { $null: true } }
+ * 
+ * Note: $not operator is not supported. Use $ne for field-level negation.
  */
 export type Filter = FilterCondition;