Refactor Fritz!Box plugin: move imports to module level

The fritzconnection imports were originally placed inside the function
bodies as a defensive pattern: by catching ImportError locally,
get_fritzbox_connection() and get_connected_devices() could each return
None or an empty list with a user-friendly log message instead of
crashing at import time. This kept the plugin runnable even when the
dependency was missing.

Requested by reviewer jokob-sk in PR #1592: move all imports to the top
of the module, treating fritzconnection as a required dependency that is
assumed to be installed via requirements.txt.

Changes:
- Add top-level imports for FritzConnection and FritzHosts
  (fritzbox.py:16-17)

- Remove inline import and ImportError handler from
  get_fritzbox_connection() (fritzbox.py:48, 64-67)

- Remove inline import and ImportError handler from
  get_connected_devices() (fritzbox.py:79, 133-134)

Functional behavior of the plugin is unchanged.

front/plugins/fritzbox/fritzbox.py

@@ -13,6 +13,8 @@ from const import logPath  # noqa: E402, E261 [flake8 lint suppression]
 from plugin_helper import Plugin_Objects, normalize_mac  # noqa: E402, E261 [flake8 lint suppression]
 from logger import mylog, Logger  # noqa: E402, E261 [flake8 lint suppression]
 from helper import get_setting_value  # noqa: E402, E261 [flake8 lint suppression]
+from fritzconnection import FritzConnection  # noqa: E402, E261 [flake8 lint suppression]
+from fritzconnection.lib.fritzhosts import FritzHosts  # noqa: E402, E261 [flake8 lint suppression]
 
 import conf  # noqa: E402, E261 [flake8 lint suppression]
 
@@ -44,8 +46,6 @@ def get_fritzbox_connection(host, port, user, password, use_tls):
     Returns: FritzConnection object or None on failure
     """
     try:
-        from fritzconnection import FritzConnection
-
         mylog('verbose', [f'[{pluginName}] Attempting connection to {host}:{port} (TLS: {use_tls})'])
 
         fc = FritzConnection(
@@ -61,10 +61,6 @@ def get_fritzbox_connection(host, port, user, password, use_tls):
         mylog('verbose', [f'[{pluginName}] Model: {fc.modelname}, Software: {fc.system_version}'])
 
         return fc
-    except ImportError as e:
-        mylog('none', [f'[{pluginName}] ⚠ ERROR: fritzconnection library not installed: {e}'])
-        mylog('none', [f'[{pluginName}] Please install with: pip install fritzconnection'])
-        return None
     except Exception as e:
         mylog('none', [f'[{pluginName}] ⚠ ERROR: Failed to connect to Fritz!Box: {e}'])
         mylog('none', [f'[{pluginName}] Check host ({host}), port ({port}), and credentials'])
@@ -82,8 +78,6 @@ def get_connected_devices(fc, active_only):
     devices = []
 
     try:
-        from fritzconnection.lib.fritzhosts import FritzHosts
-
         hosts = FritzHosts(fc)
         host_count = hosts.host_numbers
 
@@ -136,8 +130,6 @@ def get_connected_devices(fc, active_only):
 
         mylog('verbose', [f'[{pluginName}] Processed {len(devices)} devices'])
 
-    except ImportError as e:
-        mylog('none', [f'[{pluginName}] ⚠ ERROR: fritzconnection library not properly installed: {e}'])
     except Exception as e:
         mylog('none', [f'[{pluginName}] ⚠ ERROR: Failed to query devices: {e}'])