Move imports to module level (PLC0415 fix)

Fix PLC0415 'import should be at top-level of a file' errors:
- Move Quantity, TextParser, MappingTextParser imports to top of xml_parser.py
- Move potcar_quantities import to top level
- Move numpy and Quantity imports to top of vasp.py schema

These imports were previously inside conditional blocks or class definitions,
which triggered PLC0415 warnings in CI (chartboost/ruff-action).

Author: ndaelman-hu

src/nomad_simulation_parsers/parsers/vasp/xml_parser.py

@@ -7,11 +7,13 @@
 if TYPE_CHECKING:
     pass
 
-from nomad.parsing.file_parser import ArchiveWriter
+from nomad.parsing.file_parser import ArchiveWriter, Quantity, TextParser
 from nomad.parsing.file_parser.mapping_parser import MetainfoParser, Path, XMLParser
+from nomad.parsing.file_parser.mapping_parser import TextParser as MappingTextParser
 from nomad.utils import get_logger
 from nomad_simulations.schema_packages.general import Simulation
 
+from nomad_simulation_parsers.parsers.vasp.outcar_parser import potcar_quantities
 from nomad_simulation_parsers.schema_packages import vasp
 
 LOGGER = get_logger(__name__)
@@ -108,15 +110,6 @@ def write_to_archive(self) -> None:
                 f'Found OUTCAR at {outcar_path}, extending vasprun.xml '
                 'pseudopotentials with detailed metadata'
             )
-            from nomad.parsing.file_parser import Quantity, TextParser
-            from nomad.parsing.file_parser.mapping_parser import (
-                TextParser as MappingTextParser,
-            )
-
-            from nomad_simulation_parsers.parsers.vasp.outcar_parser import (
-                potcar_quantities,
-            )
-
             potcar_pattern = (
                 r'POTCAR:([\s\S]+?VRHFIN[\s\S]+?)'
                 r'(?=\s*POTCAR:|\s*local pseudopotential:|\Z)'

src/nomad_simulation_parsers/schema_packages/vasp.py

@@ -1,9 +1,11 @@
 from typing import TYPE_CHECKING
 
+import numpy as np
+
 if TYPE_CHECKING:
     pass
 
-from nomad.metainfo import SchemaPackage
+from nomad.metainfo import Quantity, SchemaPackage
 from nomad_simulations.schema_packages import (
     general,
     model_method,
@@ -299,9 +301,6 @@ class ElectronicEigenvalues(outputs.ElectronicEigenvalues):
 class Pseudopotential(numerical_settings.Pseudopotential):
     """VASP-specific pseudopotential with POTCAR metadata."""
 
-    import numpy as np
-    from nomad.metainfo import Quantity
-
     sha256 = Quantity(
         type=str,
         description='SHA256 hash of POTCAR file for library identification',