feat(coverage): print a terminal coverage summary from the SimpleCov report

`make coverage` only reported the JSON's file size, so reading the real number meant opening the report by hand. I added a self-contained `scripts/coverage-summary.el` that parses the SimpleCov JSON and prints per-file covered/total lines with a percent, a line-weighted project figure, and a source-weighted figure. A tracked source missing from the report counts as 0% rather than dropping out silently, so a source that never got instrumented still shows up.

A new `coverage-summary` target runs it against the last report, and `make coverage` chains it onto the tail of a local run (CI emits coveralls.json, not simplecov.json, so it's skipped there). Covered by `tests/test-pearl-coverage-summary.el`: parser hit/executable/merge-key semantics, the per-file records, and the error paths for a missing or malformed report.

1 files changed, 2 insertions, 1 deletions

diff --git a/tests/Makefile b/tests/Makefile
index c011359..341bfdb 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -293,7 +293,8 @@ help:
 	@echo "Project-root targets (run from project root):"
 	@echo "  make setup                     - Install all deps via eask"
 	@echo "  make compile                   - Byte-compile pearl.el"
-	@echo "  make coverage                  - Generate simplecov JSON via undercover"
+	@echo "  make coverage                  - Generate simplecov JSON via undercover (+ summary)"
+	@echo "  make coverage-summary          - Print covered/total + percent from the last report"
 	@echo ""
 	@echo "Tagging tests as :slow:"
 	@echo "  (ert-deftest test-foo () :tags '(:slow) ...) — excluded by default"