Initial commit: server-monitor v1 (Python)

Kompletter Neustart als Python-Projekt.
Portiert von zfs-monitor Bash v3, saubere Architektur:
- config.py: TOML-Config mit dataclasses
- state.py: zentrales State-Management (JSON statt Einzeldateien)
- notify.py: Telegram + Persistent Alerting als wiederverwendbare Klasse
- checks/zfs.py: ZFS Pool-Health, I/O-Fehler, Kapazität
- checks/smart.py: SATA + NVMe SMART-Monitoring
- checks/nut.py: NUT/USV-Monitoring (APC Back-UPS RS 1500G)

checks/base.py

@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+import logging
+import subprocess
+from abc import ABC, abstractmethod
+
+from config import Config
+from notify import Alerter
+from state import State
+
+
+class Check(ABC):
+    def __init__(self, config: Config, state: State, alerter: Alerter) -> None:
+        self.config = config
+        self.state = state
+        self.alerter = alerter
+        self.log = logging.getLogger(self.__class__.__name__)
+
+    @abstractmethod
+    def run(self) -> None:
+        pass
+
+    def _run(self, cmd: list[str], timeout: int) -> str | None:
+        """Run command, return stdout (even on non-zero exit) or None on error."""
+        try:
+            result = subprocess.run(
+                cmd,
+                capture_output=True,
+                text=True,
+                timeout=timeout,
+            )
+            return result.stdout
+        except subprocess.TimeoutExpired:
+            self.log.warning("Timeout: %s", " ".join(cmd))
+            return None
+        except (FileNotFoundError, OSError) as e:
+            self.log.warning("Fehler bei '%s': %s", cmd[0], e)
+            return None