Move coverage scripts to scripts/ directory and add Makefile targets

Reorganize coverage tooling for better project structure and easier usage.

Changes:
- Move measure_coverage.sh and generate_coverage_html.sh to scripts/
- Add Makefile targets:
  - make coverage-report: Generate text coverage summary (5s simulation)
  - make coverage-html: Generate HTML coverage report (5s simulation)
- Update measure_coverage.sh to find generate_coverage_html.sh using relative path

Usage:
  make coverage-report    # Quick text summary
  make coverage-html      # Full HTML report with branch details

The HTML report provides interactive visualization of which branches
were taken during simulation execution, with color-coded source views.

Makefile

@@ -15,12 +15,18 @@ CFILES = $(shell find src -name '*.c')
 HFILES = $(shell find src -name '*.h')
 OFILES = $(CFILES:.c=.o)
 
-.PHONY: all clean coverage
+.PHONY: all clean coverage coverage-report coverage-html
 
 all: mousefs$(EXT) mousefs_random_test$(EXT) example_client$(EXT) libmousefs.a
 
 coverage: mousefs_random_test_coverage$(EXT)
 
+coverage-report:
+	@./scripts/measure_coverage.sh 5
+
+coverage-html:
+	@./scripts/measure_coverage.sh 5 --html
+
 mousefs$(EXT): $(CFILES) $(HFILES)
 	gcc -o $@ $(CFILES) $(CFLAGS) $(LFLAGS) -Iinc -DBUILD_SERVER