fix: correct zero-safe pathconf checks and connectivity prefix match

- Use `is not None` for pathconf values so 0 is not silently dropped
- Broaden connectivity prefix check to catch bare "connectivity" key

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

hbd/client/plugins/filesystem_info.py

@@ -127,15 +127,15 @@ class FilesystemInfoPlugin(InfoPlugin):
                     try:
                         # Maximum filename length
                         max_name = os.pathconf(partition.mountpoint, 'PC_NAME_MAX')
-                        if max_name:
+                        if max_name is not None:
                             fs_info['maxfile'] = max_name
                     except (OSError, ValueError):
                         pass
-                    
+
                     try:
                         # Maximum path length
                         max_path = os.pathconf(partition.mountpoint, 'PC_PATH_MAX')
-                        if max_path:
+                        if max_path is not None:
                             fs_info['maxpath'] = max_path
                     except (OSError, ValueError):
                         pass

hbd/server/threshold.py

@@ -1556,7 +1556,7 @@ class ThresholdChecker:
             for mp in host.alert_states:
                 # connectivity.* and rtt are managed by the connection state
                 # machine, not by threshold config — never purge them.
-                if mp == "rtt" or mp.startswith("connectivity."):
+                if mp == "rtt" or mp.startswith("connectivity"):
                     continue
                 if self._find_threshold(configured, mp)[0] is not None:
                     continue