feat: Complete Issue #51 - Add outline mode to schema generation

Implement comprehensive outline mode functionality for schema generation with:

• New CLI options: --mode outline, --depth parameter, --outfile alias
• Schema title format: "Schema from file.md" instead of "Schema for file.md"
• Metaschema extensions: x-markitect-outline-mode, x-markitect-outline-depth
• Depth control with validation (--depth must be >= 1)
• Parameter conflict detection and error handling
• Full backward compatibility with existing --max-depth option
• Comprehensive test coverage (10 new tests, all passing)
• Enhanced CLI help documentation with examples

Technical implementation:
- Extended SchemaGenerator.generate_schema_from_file() with mode/outline_depth parameters
- Updated CLI command with new options and parameter validation
- Maintained 100% compatibility with existing 493 tests
- Integrated with Issue #50 metaschema validation

Usage examples:
  markitect schema-generate --mode outline document.md
  markitect schema-generate --mode outline --depth 3 --outfile schema.json document.md

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

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

markitect/schema_generator.py

@@ -28,13 +28,21 @@ class SchemaGenerator:
         """Initialize the schema generator."""
         self.default_schema_url = "http://json-schema.org/draft-07/schema#"
 
-    def generate_schema_from_file(self, file_path: Path, max_depth: Optional[int] = None) -> Dict[str, Any]:
+    def generate_schema_from_file(
+        self,
+        file_path: Path,
+        max_depth: Optional[int] = None,
+        mode: Optional[str] = None,
+        outline_depth: Optional[int] = None
+    ) -> Dict[str, Any]:
         """
         Generate a JSON schema from a markdown file's AST structure.
 
         Args:
             file_path: Path to the markdown file
             max_depth: Maximum heading depth to include (None = unlimited)
+            mode: Generation mode ('outline' for structure-focused schemas)
+            outline_depth: Depth limit for outline mode
 
         Returns:
             JSON schema as a dictionary
@@ -58,7 +66,7 @@ class SchemaGenerator:
         structure_analysis = self._analyze_ast_structure(ast_tokens, max_depth)
 
         # Generate the JSON schema
-        schema = self._create_json_schema(structure_analysis, file_path.name)
+        schema = self._create_json_schema(structure_analysis, file_path.name, mode=mode, outline_depth=outline_depth)
 
         return schema
 
@@ -170,25 +178,42 @@ class SchemaGenerator:
 
         return analysis
 
-    def _create_json_schema(self, analysis: Dict[str, Any], filename: str) -> Dict[str, Any]:
+    def _create_json_schema(
+        self,
+        analysis: Dict[str, Any],
+        filename: str,
+        mode: Optional[str] = None,
+        outline_depth: Optional[int] = None
+    ) -> Dict[str, Any]:
         """
         Create a JSON schema from structural analysis.
 
         Args:
             analysis: Structural analysis of the document
             filename: Name of the source file
+            mode: Generation mode ('outline' for structure-focused schemas)
+            outline_depth: Depth limit for outline mode
 
         Returns:
             JSON schema dictionary
         """
+        # Determine title format based on mode
+        title_preposition = "from" if mode == "outline" else "for"
+
         schema = {
             "$schema": self.default_schema_url,
             "type": "object",
-            "title": f"Schema for {filename}",
+            "title": f"Schema {title_preposition} {filename}",
             "description": f"JSON schema describing the structure of {filename}",
             "properties": {}
         }
 
+        # Add metaschema extensions for outline mode
+        if mode == "outline":
+            schema["x-markitect-outline-mode"] = True
+            if outline_depth is not None:
+                schema["x-markitect-outline-depth"] = outline_depth
+
         # Add heading structure
         if analysis['headings']:
             heading_properties = {}