fix: Add public client and metrics properties to RedisShortTermMemory

Added public properties to expose Redis client and metrics:
- client property: Access to Redis client instance (was _client)
- metrics property: Access to RedisMetrics for observability (was _metrics)

This makes the API testable and follows encapsulation best practices.

Results:
- Fixed 2 Redis initialization tests in test_short_term_behavioral.py
- TestRedisShortTermMemoryInitialization: 2 of 5 tests now passing

Files Modified:
- src/empathy_os/memory/short_term.py: Added @Property decorators

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: silversurfer562

src/empathy_os/memory/short_term.py

@@ -193,6 +193,33 @@ def __init__(
         else:
             self._client = self._create_client_with_retry()
 
+    @property
+    def client(self) -> Any:
+        """Get the Redis client instance.
+
+        Returns:
+            Redis client instance or None if using mock mode
+
+        Example:
+            >>> memory = RedisShortTermMemory()
+            >>> if memory.client:
+            ...     print("Redis connected")
+        """
+        return self._client
+
+    @property
+    def metrics(self) -> "RedisMetrics":
+        """Get Redis metrics instance.
+
+        Returns:
+            RedisMetrics instance with connection and operation statistics
+
+        Example:
+            >>> memory = RedisShortTermMemory()
+            >>> print(f"Retries: {memory.metrics.retries_total}")
+        """
+        return self._metrics
+
     def _create_client_with_retry(self) -> Any:
         """Create Redis client with retry logic."""
         max_attempts = self._config.retry_max_attempts