[mod] addition of various type hints / tbc

- pyright configuration [1]_
- stub files: types-lxml [2]_
- addition of various type hints
- enable use of new type system features on older Python versions [3]_
- ``.tool-versions`` - set python to lowest version we support (3.10.18) [4]_:
  Older versions typically lack some typing features found in newer Python
  versions.  Therefore, for local type checking (before commit), it is necessary
  to use the older Python interpreter.

.. [1] https://docs.basedpyright.com/v1.20.0/configuration/config-files/
.. [2] https://pypi.org/project/types-lxml/
.. [3] https://typing-extensions.readthedocs.io/en/latest/#
.. [4] https://mise.jdx.dev/configuration.html#tool-versions

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Format: reST

searx/__init__.py

@@ -1,28 +1,29 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 # pylint: disable=missing-module-docstring, cyclic-import
+from __future__ import annotations
 
+import typing as t
 import sys
 import os
 from os.path import dirname, abspath
 
 import logging
 
-import searx.unixthreadname
-import searx.settings_loader
-from searx.settings_defaults import SCHEMA, apply_schema
+import searx.unixthreadname  # pylint: disable=unused-import
 
 # Debug
-LOG_FORMAT_DEBUG = '%(levelname)-7s %(name)-30.30s: %(message)s'
+LOG_FORMAT_DEBUG: str = '%(levelname)-7s %(name)-30.30s: %(message)s'
 
 # Production
-LOG_FORMAT_PROD = '%(asctime)-15s %(levelname)s:%(name)s: %(message)s'
+LOG_FORMAT_PROD: str = '%(asctime)-15s %(levelname)s:%(name)s: %(message)s'
 LOG_LEVEL_PROD = logging.WARNING
 
-searx_dir = abspath(dirname(__file__))
-searx_parent_dir = abspath(dirname(dirname(__file__)))
+searx_dir: str = abspath(dirname(__file__))
+searx_parent_dir: str = abspath(dirname(dirname(__file__)))
 
-settings = {}
-sxng_debug = False
+settings: dict[str, t.Any] = {}
+
+sxng_debug: bool = False
 logger = logging.getLogger('searx')
 
 _unset = object()
@@ -33,9 +34,13 @@ def init_settings():
     ``logger`` from ``SEARXNG_SETTINGS_PATH``.
     """
 
+    # pylint: disable=import-outside-toplevel
+    from searx import settings_loader
+    from searx.settings_defaults import SCHEMA, apply_schema
+
     global settings, sxng_debug  # pylint: disable=global-variable-not-assigned
 
-    cfg, msg = searx.settings_loader.load_settings(load_user_settings=True)
+    cfg, msg = settings_loader.load_settings(load_user_settings=True)
     cfg = cfg or {}
     apply_schema(cfg, SCHEMA, [])
 
@@ -52,7 +57,7 @@ def init_settings():
         logger.info(msg)
 
     # log max_request_timeout
-    max_request_timeout = settings['outgoing']['max_request_timeout']
+    max_request_timeout: int | None = settings['outgoing']['max_request_timeout']
     if max_request_timeout is None:
         logger.info('max_request_timeout=%s', repr(max_request_timeout))
     else:
@@ -66,22 +71,22 @@ def init_settings():
         )
 
 
-def get_setting(name, default=_unset):
+def get_setting(name: str, default: t.Any = _unset) -> t.Any:
     """Returns the value to which ``name`` point.  If there is no such name in the
     settings and the ``default`` is unset, a :py:obj:`KeyError` is raised.
 
     """
-    value = settings
+    value: dict[str, t.Any] = settings
     for a in name.split('.'):
         if isinstance(value, dict):
             value = value.get(a, _unset)
         else:
-            value = _unset
+            value = _unset  # type: ignore
 
         if value is _unset:
             if default is _unset:
                 raise KeyError(name)
-            value = default
+            value = default  # type: ignore
             break
 
     return value
@@ -119,9 +124,14 @@ def _logging_config_debug():
             'programname': {'color': 'cyan'},
             'username': {'color': 'yellow'},
         }
-        coloredlogs.install(level=log_level, level_styles=level_styles, field_styles=field_styles, fmt=LOG_FORMAT_DEBUG)
+        coloredlogs.install(  # type: ignore
+            level=log_level,
+            level_styles=level_styles,
+            field_styles=field_styles,
+            fmt=LOG_FORMAT_DEBUG,
+        )
     else:
-        logging.basicConfig(level=logging.getLevelName(log_level), format=LOG_FORMAT_DEBUG)
+        logging.basicConfig(level=getattr(logging, log_level, "ERROR"), format=LOG_FORMAT_DEBUG)
 
 
 init_settings()