Wire up live <mysql> for vst/modular1/modular1_patches, without <database>

<database> was SESSIONCTL.tag's own JET-1.4-only concept - the new JetCore
port never implemented it. The real, dispatched tag for opening a MySQL
connection is <mysql> (confirmed in Tag.cpp's dispatch chain), so these 3
product pages - the ones deferred in the previous conversion pass because
they pull live rows via <sql> - now wrap their content in a real
<mysql host="localhost" database="barant" user="barant" password="...">
matching barant.com's own config.cfg, with <retain> (a SESSIONCTL-only
form-echo helper with no analog here) stripped.

host="localhost" is correct per config.cfg but only reachable from
barant.com itself - a locally-run .jtc genuinely cannot connect from here.
That's intentional: the connection fails at runtime exactly as if the
database were down, and APIServer's existing catch(coreutils::Exception)
path (ApiSession.cpp) already turns that into a clean 500 rather than a
crash - verified live: all 3 pages return HTTP 500 with mysql's own
"database and host parameters are not valid." message, and the server
process stays up and responsive throughout.

The real DB password is deliberately not a literal in this file - it's
read from BARANT_DB_PASSWORD at conversion time, and the resulting .jet
output for these 3 pages is gitignored rather than committed, so the
credential never enters git history even though it does end up baked into
the locally-generated, locally-deployed .jtc.

.gitignore

@@ -27,3 +27,11 @@ jetc/*.compiled.cpp
 jetc/*.pic.o
 jetc/*.jtc
 jetc/libCoreUtils_pic.a
+
+# These 3 pages' converted output bakes in a real barant.com DB password
+# (via BARANT_DB_PASSWORD at conversion time - see convert.py's MYSQL_PAGES
+# handling) so they never enter git history, unlike the rest of
+# jetc/barant-site/jet/, which is plain static content and safe to commit.
+jetc/barant-site/jet/vst.jet
+jetc/barant-site/jet/modular1.jet
+jetc/barant-site/jet/modular1_patches.jet