Fix ping latency to use actual RTT instead of subprocess time

Parse the real RTT from ping output instead of measuring subprocess
execution time, which included process startup overhead.

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

checkers/ping.py

@@ -4,8 +4,8 @@ Checker Ping.
 Vérifie la disponibilité d'un hôte via ICMP ping.
 """
 
+import re
 import subprocess
-import time
 import platform
 
 from .base import BaseChecker, CheckResult
@@ -41,7 +41,6 @@ class PingChecker(BaseChecker):
         else:
             cmd = ["ping", "-c", str(count), "-W", str(timeout), host]
 
-        start = time.time()
         try:
             result = subprocess.run(
                 cmd,
@@ -49,9 +48,12 @@ class PingChecker(BaseChecker):
                 text=True,
                 timeout=timeout + 5
             )
-            response_time = (time.time() - start) * 1000  # ms
 
             if result.returncode == 0:
+                # Parse RTT from ping output (e.g., "time=0.32 ms" or "time=0.32ms")
+                match = re.search(r"time[=<]([\d.]+)\s*ms", result.stdout)
+                response_time = float(match.group(1)) if match else None
+
                 return CheckResult(
                     success=True,
                     message="Host is reachable",