Add venv for only pre-commit

This dedicated virtual environment is intended to persist through
`make clean`, not disrupting the ability to run regular Git commits if
the "primary" virtual environment is removed.  The `pre-commit`
experience it produces should align make- and local-venv-oriented users
with users who have a more global availability of `pre-commit`.

References:
* casework/CASE-Utilities-Python#37

Signed-off-by: Alex Nelson <alexander.nelson@nist.gov>

Author: ajnelson-nist

.gitignore

@@ -15,4 +15,5 @@ catalog-v001.xml
 
 # Workflow files
 .*.done.log
+.venv-pre-commit
 venv

Makefile

@@ -16,7 +16,8 @@ SHELL := /bin/bash
 PYTHON3 ?= $(shell which python3.9 2>/dev/null || which python3.8 2>/dev/null || which python3.7 2>/dev/null || which python3.6 2>/dev/null || which python3)
 
 all: \
-  .dependencies.done.log
+  .dependencies.done.log \
+  .venv-pre-commit/var/.pre-commit-built.log
 	$(MAKE) \
 	  --directory examples/illustrations
 
@@ -64,6 +65,29 @@ all: \
 	  .lib.done.log
 	touch $@
 
+# This virtual environment is meant to be built once and then persist, even through 'make clean'.
+# If a recipe is written to remove this flag file, it should first run `pre-commit uninstall`.
+.venv-pre-commit/var/.pre-commit-built.log:
+	rm -rf .venv-pre-commit
+	test -r .pre-commit-config.yaml \
+	  || (echo "ERROR:Makefile:pre-commit is expected to install for this repository, but .pre-commit-config.yaml does not expect to exist." >&2 ; exit 1)
+	$(PYTHON3) -m venv \
+	  .venv-pre-commit
+	source .venv-pre-commit/bin/activate \
+	  && pip install \
+	    --upgrade \
+	    pip \
+	    setuptools \
+	    wheel
+	source .venv-pre-commit/bin/activate \
+	  && pip install \
+	    pre-commit
+	source .venv-pre-commit/bin/activate \
+	  && pre-commit install
+	mkdir -p \
+	  .venv-pre-commit/var
+	touch $@
+
 .venv.done.log: \
   .git_submodule_init.done.log \
   requirements.txt
@@ -85,7 +109,8 @@ all: \
 	touch $@
 
 check: \
-  .dependencies.done.log
+  .dependencies.done.log \
+  .venv-pre-commit/var/.pre-commit-built.log
 	$(MAKE) \
 	  --directory examples/illustrations \
 	  check