Add unit tests for analytics, fallback client, and refactored validators

- Implemented comprehensive unit tests for the BuddAI Analytics module, covering fallback statistics calculations.
- Created tests for the FallbackClient to ensure proper escalation to various AI models and handling of missing API keys.
- Developed unit tests for the refactored validator system, validating various hardware and coding standards.
- Established a base validator interface and implemented specific validators for ESP32, Arduino, motor control, memory safety, and more.
- Enhanced the validator registry to auto-discover and manage validators effectively.
- Included detailed validation logic for common issues in embedded systems programming, such as unused variables, safety timeouts, and coding style violations.

validators/base_validator.py

@@ -0,0 +1,40 @@
+"""
+Base validator interface
+All validators inherit from this
+"""
+
+class BaseValidator:
+    """Base class for all validators"""
+    
+    name = "Base Validator"
+    triggers = []  # Keywords that activate this validator
+    priority = 5   # 1=critical, 10=nice-to-have
+    
+    def validate(self, code: str, context: dict) -> list:
+        """
+        Validate code and return issues
+        
+        Args:
+            code: The code to validate
+            context: Dict with hardware, libraries, etc.
+            
+        Returns:
+            List of issue dicts:
+            {
+                'severity': 'error|warning|info',
+                'line': line_number or None,
+                'message': 'What is wrong',
+                'fix': 'How to fix it'
+            }
+        """
+        raise NotImplementedError
+    
+    def matches_context(self, code: str, context: dict) -> bool:
+        """
+        Check if this validator should run
+        
+        Returns:
+            bool: True if any trigger keyword in code
+        """
+        code_lower = code.lower()
+        return any(trigger.lower() in code_lower for trigger in self.triggers)