chore(tooling): exclude scripts/_dev/ from ruff and mypy

Pre-flight for the judge-layer v1 PR: scripts/_dev/ will hold sklearn-
dependent fixture-generation tooling that imports packages not in the
project's runtime dependencies. Excluding the directory now prevents
ruff/mypy false positives when those scripts land in Phase 4.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -54,6 +54,7 @@ testpaths = ["tests"]
 [tool.ruff]
 target-version = "py311"
 line-length = 100
+extend-exclude = ["scripts/_dev"]
 
 [tool.ruff.lint]
 select = ["E", "F", "I", "N", "W"]
@@ -62,3 +63,4 @@ select = ["E", "F", "I", "N", "W"]
 python_version = "3.11"
 warn_return_any = true
 warn_unused_configs = true
+exclude = ["scripts/_dev/"]