Drop event dict keys colliding with LogRecord attributes in render_to_log_*

render_to_log_kwargs() and render_to_log_args_and_kwargs() build the
extra kwarg straight out of whatever is left in the event dict once the
event, positional_args, and the exc_info/stack_info/stacklevel trio have
been extracted. If a remaining key happens to share a name with an
attribute that logging.LogRecord already carries (filename, module,
process, message, ...), logging.Logger.makeRecord() rejects the whole
call with a raw KeyError, crashing a documented, non-ProcessorFormatter
configuration on an entirely plausible business field name.

structlog.stdlib.ExtraAdder already filters LogRecord's own attribute
names out of the event dict when merging a record's extra fields in the
other direction. Apply the same filtering here so a colliding key is
dropped from extra instead of reaching logging.Logger.makeRecord() and
crashing it.

Fixes #486.

CHANGELOG.md

@@ -15,6 +15,11 @@ You can find our backwards-compatibility policy [here](https://github.com/hynek/
 
 ## [Unreleased](https://github.com/hynek/structlog/compare/26.1.0...HEAD)
 
+### Fixed
+
+- `structlog.stdlib.render_to_log_kwargs()` and `structlog.stdlib.render_to_log_args_and_kwargs()` now drop event dict keys that collide with a `logging.LogRecord` attribute (for example `filename` or `module`) instead of crashing the standard library with `KeyError: "Attempt to overwrite '...' in LogRecord"`.
+  [#486](https://github.com/hynek/structlog/issues/486)
+
 
 ## [26.1.0](https://github.com/hynek/structlog/compare/25.5.0...26.1.0) - 2026-06-06