feat: add Guided Learning Paths feature

Implement PathManager to orchestrate multi-module learning journeys:
- Add PathManager class with start/pause/resume functionality
- Create learning-paths.json config with CSS Fundamentals path
- Integrate path progress tracking with LessonEngine
- Add path selection UI to homepage and navigation
- Include JSON schema for learning path validation
- Add comprehensive test suite for PathManager

schemas/learning-path-schema.json

@@ -0,0 +1,56 @@
+{
+	"$schema": "http://json-schema.org/draft-07/schema#",
+	"title": "Code Crispies Learning Path Schema",
+	"description": "Schema for guided learning paths that organize modules into structured learning sequences",
+	"type": "object",
+	"required": ["id", "title", "goal", "estimatedTime", "difficulty", "modules"],
+	"properties": {
+		"id": {
+			"type": "string",
+			"description": "Unique identifier for the learning path",
+			"pattern": "^[a-z0-9-]+$"
+		},
+		"title": {
+			"type": "string",
+			"description": "Display title of the learning path",
+			"minLength": 1,
+			"maxLength": 100
+		},
+		"goal": {
+			"type": "string",
+			"description": "Clear description of what the learner will achieve by completing this path",
+			"minLength": 1,
+			"maxLength": 500
+		},
+		"estimatedTime": {
+			"type": "integer",
+			"description": "Estimated time to complete the path in minutes",
+			"minimum": 1
+		},
+		"difficulty": {
+			"type": "string",
+			"enum": ["beginner", "intermediate", "advanced"],
+			"description": "Overall difficulty level of the learning path"
+		},
+		"modules": {
+			"type": "array",
+			"description": "Ordered array of module IDs that comprise this learning path",
+			"minItems": 1,
+			"items": {
+				"type": "string",
+				"description": "Module ID that references an existing module",
+				"pattern": "^[a-z0-9-]+$"
+			}
+		},
+		"prerequisites": {
+			"type": "array",
+			"description": "Optional array of learning path IDs that should be completed before this one",
+			"default": [],
+			"items": {
+				"type": "string",
+				"description": "Learning path ID that should be completed first",
+				"pattern": "^[a-z0-9-]+$"
+			}
+		}
+	}
+}