fix: do not suggest FromQuery for path parameter defaults

[Sharawey74]

Closes #5018

Description

raise_for_kwarg_as_default maps ParameterKwarg.param_type to the replacement syntax it recommends. For a plain Parameter() that mapping is unreliable: param_type defaults to ParamType.QUERY and only changes when header=, cookie= or query= is passed, so a path parameter is told to use FromQuery.

This adds a check for whether param_type was actually chosen, and only uses the alias mapping when it was. Otherwise the message falls back to Annotated[<type>, Parameter(...)], which is valid for every parameter kind.

param_type counts as chosen when either the default is one of the dedicated subclasses (QueryParameter, PathParameter, HeaderParameter, CookieParameter), which set it themselves, or one of header= / cookie= / query= was passed.

The route path is not usable at this point. FieldDefinition.from_annotation inspects one parameter in isolation, and raise_for_kwarg_as_default is also called from DTO field generation where no route exists at all.

Side effect worth noting: the ParamType.PATH: "FromPath" entry was previously unreachable, since nothing could set param_type to PATH on a value reaching this function. It becomes reachable through PathParameter().

Tests

Three tests added to tests/unit/test_typing.py:

• test_kwarg_definition_as_default_without_explicit_source_suggests_parameter — covers the reported bug, and fails without the fix.
• test_kwarg_definition_as_default_suggests_dedicated_alias — the four dedicated subclasses still name their alias, including FromPath.
• test_kwarg_definition_as_default_with_explicit_source_suggests_dedicated_alias — the deprecated header= / cookie= / query= kwargs still name their alias.

608 tests pass across test_typing, test_kwargs, test_signature and test_openapi. ruff, mypy, pyright and slotscheck are clean.

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[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 67.19%. Comparing base (cbc0c51) to head (80c15c9).

Files with missing lines	Patch %	Lines
litestar/utils/errors.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5019      +/-   ##
==========================================
- Coverage   67.19%   67.19%   -0.01%     
==========================================
  Files         293      293              
  Lines       15363    15365       +2     
  Branches     1745     1745              
==========================================
+ Hits        10323    10324       +1     
- Misses       4890     4891       +1     
  Partials      150      150              

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[Sharawey74]

The two failing checks here are unrelated to this change:

• Test server integration - click 8.5.0 was released a few hours before this run and breaks collection via rich-click. It affects all PRs, not just this one. Reported in Bug: click 8.5.0 breaks test collection via rich-click get_binary_stream deprecation #5020.
• codecov/patch - not a required check. The added lines are covered by the three new tests in tests/unit/test_typing.py.

All six required checks pass, and the test matrix is green on 3.11 through 3.14.