Rparadox 0.1.2

Bug fixes and improvements

Fixed CRAN check issues on Debian: package no longer attempts to open Paradox files in write mode (rb+ → rb). This ensures full compliance with CRAN Policy (no writes outside of temporary directories).
Fixed heap-buffer-overflow in PX_get_data_alpha (discovered with AddressSanitizer). Now the function safely respects field length and prevents out-of-bounds reads for fixed-length strings without \0.
Improved handling of invalid/null Paradox dates with an upper bound filter for extreme values.
Added proper .gitignore entries for cran-comments.md and CRAN-SUBMISSION.
Updated README with CRAN badges and installation instructions.
Expanded test coverage: re-enabled datasets with German, English and Russian encodings, including CP866.

Fixed CRAN feedback:
- Removed unnecessary \dontrun{} in examples.
  Added fast, self-contained examples using demo files
  (biolife.db, of_cp866.db in inst/extdata).
- Ensured no commented-out example code remains.
- All examples now run in < 5s and without commented-out code.
Fixed vignette build issue on CRAN check servers:
- Explicitly added rmarkdown in VignetteBuilder
  to avoid failures when running with --no-suggests.
Memory management improvements:
- Fixed memory leaks in src/interface.c when reading BLOB fields.
- Examples and vignette now run cleanly under Valgrind.
Verified that all examples run in < 5 sec and vignettes build
successfully across test environments.