Escape special characters in Prometheus metric labels

Add escape function to sanitize backslashes, double quotes, and newlines
in label values per Prometheus text format spec. Prevents corrupted
metrics output from model names or paths containing these characters.

Resolves #10

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hwmonDaemon.py

@@ -3163,9 +3163,11 @@ class SystemHealthMonitor:
         hostname = health_report.get('hostname', socket.gethostname())
         metrics = []
 
-        # Helper to format labels
+        # Helper to format labels with proper Prometheus escaping
         def labels(**kwargs) -> str:
-            pairs = [f'{k}="{v}"' for k, v in kwargs.items() if v is not None]
+            def escape(value):
+                return str(value).replace('\\', '\\\\').replace('"', '\\"').replace('\n', '\\n')
+            pairs = [f'{k}="{escape(v)}"' for k, v in kwargs.items() if v is not None]
             return '{' + ','.join(pairs) + '}' if pairs else ''
 
         # === System Info ===