bible: embed only the Vulgate by default; other corpora opt-in

Split the bundled corpora so the default binary carries only the
public-domain Latin Vulgate. wuj/drb/grb move to corpora_optional/ and are
compiled in only with `-tags fullbible`, or dropped into the user corpora
dir at runtime. This keeps the distributed AGPL binary free of third-party
scripture text -- bible corpora are not covered by lectio's licence.

- bible: read corpus files/metadata from core + optional embed FS
  (embReadCorpus/embCorpusFiles); optionalFS is set only under the tag.
- config: default `versions` now reflects corpora actually available in the
  build (Vulgate first), so a vul-only binary offers no absent versions.
- Makefile: `make build` = vul only; `make build-full` embeds the rest;
  `make test` runs with -tags fullbible; check-corpora validates both dirs.
- tests: corpusmeta asserts on vul (the always-embedded corpus); the
  versions-default expectation follows availableVersions().

1 files changed, 0 insertions, 4 deletions

diff --git a/internal/bible/corpora/grb.ini b/internal/bible/corpora/grb.ini
deleted file mode 100644
index 0d297ff..0000000
--- a/internal/bible/corpora/grb.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-; lectio corpus metadata
-lang = el
-name = Greek
-psalm_system = vulgate