syrona 0.2.1

CRAN review fixes

Removed single quotes around the OMOP CDM acronym in Title and Description.
Documented the return value of load_syrona_theme(), run_app() and syrona_disconnect().
Replaced the \dontrun{} example on run_app() with an if (interactive()) block.
run_app() now restores the user’s syrona.data_dir option on exit, and the examples reset any option they set.

Added a bundled demo dataset (inst/extdata/demo): a curated 32-concept subset (conditions, procedures, drugs) that runs the full comparison workflow with no database. See RUN_DEMO.html or ?compare_all for a runnable example.
compare_all() now ships a runnable \donttest example driven by the demo data.

Shipped standard-vocabulary lookups in inst/extdata/ so a fresh install has a working conditions chapter map and procedure device/site/morphology enrichment (icd10_lookup.csv and vocabulary/*.csv, resolved via syrona_extdata()).
Dashboard “About” panel now documents all four procedure attribute filters (site, method, device, morphology) and corrects the Sex/Age filter behavior (display-only; the meta-analysis is precomputed).
Population pyramids degrade gracefully with an explanatory message when a dataset has no demographics table (e.g. the demo).
DESCRIPTION metadata polished for CRAN (Paule-Mandel reference DOI, Depends: R (>= 4.1.0)).

Corrected the fold-threshold glossary wording (similarity boundary, not a clinical-relevance boundary).