feat: move docs/_posts pages into content directory

-   and remove last vestiges of Jekyll

Author: gvwilson

.gitignore

@@ -20,4 +20,5 @@ tags
 !.gitignore
 !.npmignore
 
+docs
 tmp

code_of_conduct.md renamed to CODE_OF_CONDUCT.md

@@ -1,51 +1,53 @@
 # Manage plotly.js documentation.
 
 RUN = uv run
-DOC_SRC=docs/_posts
+HANDWRITTEN=content
 SCHEMA_SRC=test/plot-schema.json
+TMP=tmp
+EXAMPLES_DIR=${TMP}/javascript
+EXAMPLES_FILE=${EXAMPLES_DIR}/axes/index.html
+REFERENCE_DIR=${TMP}/reference
+REFERENCE_FILE=${REFERENCE_DIR}/bar/index.html
 
 ## commands: show available commands
 commands:
 	@grep -h -E '^##' ${MAKEFILE_LIST} | sed -e 's/## //g' | column -t -s ':'
 
-## doc: rebuild documentation
-.PHONY: doc
-doc:
-	make examples
-	make reference
-	make build
+## docs: rebuild documentation
+.PHONY: docs
+docs: ${EXAMPLES_FILE} ${REFERENCE_FILE}
+	${RUN} mkdocs build
 
 ## examples: build example documentation in ./tmp
-examples:
-	@mkdir -p tmp
-	${RUN} bin/example_pages.py --indir ${DOC_SRC}/plotly_js --outdir tmp/javascript --jsversion 3.2.1
-
-## format: reformat Python code
-format:
-	@ruff format bin
+examples: ${EXAMPLES_FILE}
 
-## lint: check code and project
-lint:
-	@ruff check bin
+${EXAMPLES_FILE}:
+	@mkdir -p ${TMP}
+	${RUN} bin/example_pages.py --indir ${HANDWRITTEN}/plotly_js --outdir ${EXAMPLES_DIR} --jsversion 3.2.1
 
 ## reference: build reference documentation in ./tmp
-reference:
-	@mkdir -p tmp
-	${RUN} bin/reference_pages.py --schema ${SCHEMA_SRC} --outdir tmp/reference ${DOC_SRC}/reference_pages/javascript/*.html
+reference: ${REFERENCE_FILE}
+
+${REFERENCE_FILE}:
+	@mkdir -p ${TMP}
+	${RUN} bin/reference_pages.py --schema ${SCHEMA_SRC} --outdir ${TMP}/reference ${HANDWRITTEN}/reference_pages/javascript/*.html
 
 ## serve: display documentation
 serve:
 	${RUN} mkdocs serve
 
-## website: build documentation with mkdocs using already-built examples and reference
-website:
-	${RUN} mkdocs build
-
 ## --: --
 
 ## clean: clean up repository
 clean:
 	@find . -name '*~' -delete
 	@find . -name '.DS_Store' -delete
-	@rm -rf _site
-	@rm -f ${SCHEMA_DST}
+	@rm -rf docs ${TMP}
+
+## format: reformat Python code
+format:
+	@ruff format bin
+
+## lint: check code and project
+lint:
+	@ruff check bin