fix(tax-registration): keep village picker responsive during loading ## Changes The registration region picker disabled itself for the entire initial data request, making Desa/Kelurahan appear frozen while village options loaded. Use a full-width shadcn ComboboxTrigger rendered as Button, with search inside the popup, and keep the eligible picker usable during loading. Show prerequisite guidance and region-query failures with a retry action. Preserve dependent selections when the same parent region is selected again, serialize regions by their unique IDs, and associate government field labels and descriptions with the picker. Keep the trigger label short in every state. Display the complete selected region name in an adjacent FieldDescription linked through aria-describedby, including names longer than three words. Closes #1747 Closes #1769 ## Release impact Patch. Restore the intended behavior of the existing taxpayer registration picker. ## Migration notes No database or configuration changes. The shared picker is also used by individual and company registration. ## Validation - Static UI policy checks passed: `node scripts/run-ui-checks.mjs --base d36390d8bc`. - Targeted ESLint and `git diff --check` passed. - React Doctor passed with 0 errors and 0 warnings against the full base SHA after using isolated writable cache and temporary directories: `REACT_DOCTOR_CACHE_DIR=/tmp/sapada-1756-doctor-cache TMPDIR=/tmp/sapada-1756-doctor-tmp node scripts/check-react-doctor.mjs --scope changed --base d36390d8bc72d4c9b054bb67115b58eb9b676e37`. - Both original CI failures stopped before checkout because the self-hosted runner had less than 15 GiB free. All four build-runner containers now report about 18 GiB free. No runner guard or CI configuration was changed. - Fresh [Production build](https://github.com/rafadlis/sapada/actions/runs/40274394168) and [React Doctor](https://github.com/rafadlis/sapada/actions/runs/40274394163) checks are queued for repair commit `4f0052940b`. - Build, tests, and the dev server were not run locally, per instruction. Live registration interaction remains unverified.