Fix Makefile to auto-stabilize TOC with up to 5 passes

The .songtoc file needs multiple passes to stabilize: pass 1
writes song data, pass 2 reads it into the TOC (changing page
count), pass 3+ stabilizes page references. The Makefile now
loops until the log shows no more "Rerun" warnings or max 5
passes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Makefile

@@ -1,6 +1,7 @@
 MAIN     = songbook
 ENGINE   = lualatex
 OUTDIR   = output
+TEXENV   = TEXINPUTS=.:$(shell pwd):$(shell pwd)/$(OUTDIR):
 FLAGS    = --output-directory=$(OUTDIR) --interaction=nonstopmode
 
 .PHONY: all clean distclean
@@ -10,10 +11,18 @@ all: $(OUTDIR)/$(MAIN).pdf
 $(OUTDIR):
 	mkdir -p $(OUTDIR)
 
+# Run until page references stabilize (max 5 passes).
+# The .songtoc file needs: pass 1 to write, pass 2 to read into TOC,
+# pass 3+ to stabilize page numbers after TOC page count changes.
 $(OUTDIR)/$(MAIN).pdf: $(MAIN).tex songbook-style.sty songs/*.tex | $(OUTDIR)
-	TEXINPUTS=.:$(shell pwd):$(shell pwd)/$(OUTDIR): $(ENGINE) $(FLAGS) $(MAIN).tex
-	TEXINPUTS=.:$(shell pwd):$(shell pwd)/$(OUTDIR): $(ENGINE) $(FLAGS) $(MAIN).tex
-	TEXINPUTS=.:$(shell pwd):$(shell pwd)/$(OUTDIR): $(ENGINE) $(FLAGS) $(MAIN).tex
+	@for i in 1 2 3 4 5; do \
+	  echo "=== LaTeX pass $$i ==="; \
+	  $(TEXENV) $(ENGINE) $(FLAGS) $(MAIN).tex || true; \
+	  if [ $$i -ge 3 ] && ! grep -q "Rerun" $(OUTDIR)/$(MAIN).log 2>/dev/null; then \
+	    echo "=== Stable after $$i passes ==="; \
+	    break; \
+	  fi; \
+	done
 
 clean:
 	rm -f $(OUTDIR)/*.aux $(OUTDIR)/*.log $(OUTDIR)/*.out \