feat(coverage): report modules missing from SimpleCov + project-module score

=make coverage= used to print a line-weighted percentage that only saw
files SimpleCov instrumented.  104 modules existed on disk but only 49
appeared in =.coverage/simplecov.json=, so the headline number was
flattering: untouched modules counted for nothing.

The summary script now adds two things on top of the existing report:

- A =Not in SimpleCov report= section listing modules present under
  =modules/*.el= but absent from the SimpleCov output.  Missing-module
  detection is exactly direct =modules/*.el=; subdirectories and =.elc=
  files are ignored.
- A =Project module coverage= line that is module-weighted across every
  direct =modules/*.el= file.  Tracked modules contribute their per-file
  coverage percentage; missing modules contribute 0%.

The original line-weighted SimpleCov percentage stays as the
=instrumented coverage= number.  The new module-weighted score is the
honest project-level reading: missing modules count as 0% without
inventing a fake executable-line denominator for them.

Tests assert the missing-module section, the new percentage, and the
ignore rules for .elc / nested files.

0 files changed, 0 insertions, 0 deletions