py-topdir.mk: Add test tree to default check roots

PY_CHECK_ROOTS defaults to the src and tools directories, so the ruff,
mypy, pyright, and yapf checks and the bad-pattern scan silently skip test
trees. Python tests below test/ therefore escape linting, type checking,
and formatting enforcement, even though py-check.mk itself defaults to the
whole directory when no roots are given at all.

Add $(TOPDIR)/test to the default PY_CHECK_ROOTS after the build is
through, so that the test tree receives the same checks and formatting as
src and tools. The previous commit prepared this repo's unit tests for the
strict type check and the formatter, so the extended roots pass cleanly
here.

Signed-off-by: Jan Lindemann <jan@janware.com>
Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v0.85.1

make/py-topdir.mk

@@ -9,6 +9,9 @@ MYPY_PATH_DIRECTIVE          = mypy_path = "$(MYPY_CONFIG_PATH)"
 
 ifndef PY_CHECK_ROOTS
   PY_CHECK_ROOTS             = $(wildcard $(TOPDIR)/src $(TOPDIR)/tools)
+  ifneq ($(wildcard dirs-all.done),)
+    PY_CHECK_ROOTS          += $(wildcard $(TOPDIR)/test)
+  endif
 endif
 
 all: