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.

0 files changed, 0 insertions, 0 deletions