feat: implement comprehensive query paradigm zoo system (issue #62)

- Created extensible BaseQueryParadigm interface with standardized QueryResult format
- Implemented QueryParadigmRegistry for paradigm discovery and management
- Added 5 working paradigms: SQL, FTS, GraphQL, JSONPath, Natural Language
- Documented 9 additional paradigms: QBE, Batch Manipulation, Visual Query Builder, REST API, NoSQL, UNIX Pipeline, XPath/XQuery, RAG, Data Transformation
- Integrated full CLI interface: list, search, show, exec, categories commands
- Added comprehensive test suite with 23 test cases covering all components
- Auto-registration system enables easy addition of new paradigms
- Organized paradigms by category (structural, textual, semantic, visual, procedural, network) and complexity (beginner, intermediate, advanced)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

markitect/query_paradigms/paradigms/qbe_paradigm.py

@@ -0,0 +1,116 @@
+"""
+Query By Example (QBE) Paradigm - Visual template-based querying.
+"""
+
+import time
+from typing import Dict, Any, List, Optional
+
+from ..base import BaseQueryParadigm, QueryResult
+
+
+class QueryByExampleParadigm(BaseQueryParadigm):
+    """Query By Example paradigm for visual template-based data filtering."""
+
+    @property
+    def name(self) -> str:
+        return "Query By Example"
+
+    @property
+    def description(self) -> str:
+        return "Visual template-based queries where users fill in example values to define search criteria"
+
+    @property
+    def category(self) -> str:
+        return "visual"
+
+    @property
+    def complexity(self) -> str:
+        return "beginner"
+
+    def execute(self, query: str, config: Dict[str, Any] = None) -> QueryResult:
+        """Execute QBE query (not yet implemented)."""
+        start_time = time.time()
+
+        # This is a documentation paradigm - not yet implemented
+        execution_time = (time.time() - start_time) * 1000
+
+        return QueryResult(
+            paradigm=self.name,
+            query=query,
+            execution_time_ms=execution_time,
+            result_count=0,
+            results=[],
+            metadata={
+                "status": "not_implemented",
+                "implementation_issue": "TBD - to be created",
+                "description": "QBE provides a visual interface where users create templates with example values to define search criteria"
+            },
+            success=False,
+            error_message="Query By Example paradigm not yet implemented. This paradigm will provide visual templates for filtering data."
+        )
+
+    def get_examples(self) -> List[Dict[str, str]]:
+        """Get example QBE templates."""
+        return [
+            {
+                "name": "Filter by author",
+                "description": "Template to find files by specific author",
+                "query": "{'author': 'John Smith', 'type': '*.md'}"
+            },
+            {
+                "name": "Date range filter",
+                "description": "Template to find files within date range",
+                "query": "{'created_after': '2024-01-01', 'created_before': '2024-12-31'}"
+            },
+            {
+                "name": "Tag-based filter",
+                "description": "Template to find files with specific tags",
+                "query": "{'tags': ['documentation', 'api'], 'status': 'published'}"
+            },
+            {
+                "name": "Content pattern",
+                "description": "Template to find files matching content patterns",
+                "query": "{'content_contains': 'function', 'file_extension': '.py'}"
+            }
+        ]
+
+    def validate_query(self, query: str) -> tuple[bool, Optional[str]]:
+        """Validate QBE template structure."""
+        try:
+            import json
+            template = json.loads(query)
+            if not isinstance(template, dict):
+                return False, "QBE template must be a JSON object"
+            return True, None
+        except json.JSONDecodeError:
+            return False, "QBE template must be valid JSON"
+
+    def get_syntax_help(self) -> str:
+        """Get syntax help for QBE."""
+        return """Query By Example (QBE) Syntax:
+
+QBE uses JSON templates where you specify example values for the fields you want to filter by:
+
+Structure:
+{
+  "field_name": "example_value",
+  "another_field": "another_value"
+}
+
+Supported Fields:
+- author: Author name
+- type: File type/extension
+- tags: Array of tags
+- created_after/created_before: Date filters
+- content_contains: Text that should appear in content
+- file_extension: Specific file extensions
+
+Example:
+{
+  "author": "Alice Johnson",
+  "tags": ["tutorial", "beginner"],
+  "created_after": "2024-01-01"
+}
+
+This template finds files by Alice Johnson with tutorial and beginner tags created after Jan 1, 2024.
+"""