Move bulletin into bulletins dir; adjust Makefile

This Makefile sets us up for processing multiple bulletins in the same directory.

Makefile

@@ -1,12 +1,18 @@
-all: output/bulletin.pdf
+all: output/2025-08-10.pdf
 
-output/bulletin.tex: bulletin.lytex
+output/2025-08-10.pdf: bulletins/2025-08-10.lytex output cache
-	lilypond-book --output=output --pdf bulletin.lytex
+	date=$(basename $(notdir $@)); \
+	lilypond-book --output=cache --pdf bulletins/$$date.lytex && \
+	(cd cache && lualatex $$date.tex) && \
+	mv cache/$$date.pdf output/
 
-output/bulletin.pdf: output/bulletin.tex
+output:
-	cd output && lualatex bulletin.tex
+	mkdir output
+
+cache:
+	mkdir cache
 
 clean:
-	rm -rf output
+	rm -rf output cache
 
 .PHONY: all clean