mapSpain 1.2.0

• Refactored internal helpers for downloading and reading geospatial files,
  SIANE file handling, EPSG validation, subdivision-code filtering, municipal
  metadata enrichment, empty-result messages and Canary Islands displacement.
  This is intended to simplify maintenance without changing the public API.
• Consolidated repeated Autonomous Community or City, province and municipality
  metadata across GISCO, SIANE, simplified and gridmap getters.
• Further simplified internal cache handling, sf output finalization, WMTS
  tile retrieval, dictionary translation and no-match messages. These changes
  are intended to improve maintainability without changing user-facing behavior.
• Reviewed roxygen2 documentation, generated Rd files and prose documentation
  for consistent terminology and clearer user-facing messages. This work was
  completed with AI assistance and human review.
• This internal refactor was developed with AI assistance and reviewed through
  focused package checks, including devtools::load_all() followed by
  lintr::lint_package().

What's Changed

• Bump codecov/codecov-action from 5 to 6 by @dependabot[bot] in #136
• Refactor internal helpers by @dieghernan in #138
• [codex] Use local article cache by @dieghernan in #139

Full Changelog: v1.1.0...v1.2.0