fix: resolve external_dirs relative to HERMES_HOME instead of cwd (#9949)

Relative entries in skills.external_dirs were resolved against the
process cwd via Path.resolve(), making them silently fail when Hermes
was launched from a different directory.

Resolve relative paths against get_hermes_home() for consistent
behavior across CLI, gateway, and cron contexts. Absolute paths
and env-var/tilde expansion are unchanged.

agent/skill_utils.py

@@ -200,6 +200,9 @@ def get_external_skills_dirs() -> List[Path]:
     if not isinstance(raw_dirs, list):
         return []
 
+    from hermes_constants import get_hermes_home
+
+    hermes_home = get_hermes_home()
     local_skills = get_skills_dir().resolve()
     seen: Set[Path] = set()
     result: List[Path] = []
@@ -210,7 +213,12 @@ def get_external_skills_dirs() -> List[Path]:
             continue
         # Expand ~ and environment variables
         expanded = os.path.expanduser(os.path.expandvars(entry))
-        p = Path(expanded).resolve()
+        p = Path(expanded)
+        # Resolve relative paths against HERMES_HOME, not cwd
+        if not p.is_absolute():
+            p = (hermes_home / p).resolve()
+        else:
+            p = p.resolve()
         if p == local_skills:
             continue
         if p in seen: