fix(plugins): one unreadable plugin child no longer aborts iter_plugin_dirs or memory-provider discovery

iter_plugin_dirs stat'd <child>/__init__.py inside every plugin dir, so a
single mode-000 / ACL-denied $HERMES_HOME/plugins/<x> still raised
PermissionError out of the loader, memory-provider discovery (dashboard
memory settings, hermes memory setup, plugins memory picker) and the
user cron-provider scan. Catch OSError per child and log the same
'Skipping unreadable plugin directory' warning the list path already emits.

Part of #111804

plugins/memory/__init__.py

@@ -62,12 +62,13 @@ def _get_project_plugins_dir() -> Optional[Path]:
 def _is_memory_provider_dir(path: Path) -> bool:
     """Cheap text heuristic (no import): ``__init__.py`` mentions the memory provider contract."""
     init_file = path / "__init__.py"
-    if not init_file.exists():
-        return False
     try:
+        if not init_file.exists():
+            return False
         source = init_file.read_text(errors="replace", encoding="utf-8")[:8192]
         return "register_memory_provider" in source or "MemoryProvider" in source
-    except Exception:
+    except OSError as exc:  # one mode-000 / ACL-denied child must not abort discovery
+        logger.warning("Skipping unreadable plugin directory %s: %s", path, exc)
         return False
 
 

plugins/plugin_loader.py

@@ -13,6 +13,8 @@ import sys
 from pathlib import Path
 from typing import Any, Callable, List, Optional, Tuple
 
+_log = logging.getLogger(__name__)
+
 _PLUGINS_ROOT = Path(__file__).parent
 
 
@@ -39,8 +41,16 @@ def iter_plugin_dirs(root: Path) -> List[Path]:
     """Sorted child dirs of *root* that have an ``__init__.py`` (skips ``_``/``.`` names)."""
     if not root.is_dir():
         return []
-    return [child for child in sorted(root.iterdir())
-            if child.is_dir() and not child.name.startswith(("_", ".")) and (child / "__init__.py").exists()]
+    dirs: List[Path] = []
+    for child in sorted(root.iterdir()):
+        if child.name.startswith(("_", ".")):
+            continue
+        try:
+            if child.is_dir() and (child / "__init__.py").exists():
+                dirs.append(child)
+        except OSError as exc:  # one mode-000 / ACL-denied child must not abort the listing
+            _log.warning("Skipping unreadable plugin directory %s: %s", child, exc)
+    return dirs
 
 
 def read_plugin_description(plugin_dir: Path) -> str: