[aaroncostapix]

Summary

Fixes #415.

When scan() is combined with scalar numeric store_into(), the destination was parsed again using the default decimal parser, causing valid non-decimal inputs to fail and potentially adding duplicate entries to the parsed-value history.

This change uses the configured scan parser for destination storage at the registered action position. A dedicated storage_action preserves action ordering and exception behavior without introducing duplicate stored values or triggering the resizing and truncation associated with ordinary void actions during repeated (.append()) argument parsing.

Tests

• Added regression coverage for numeric scan formats (x, X, o, b, u, i, and a) and invalid-input rejection.
• Verified action ordering and exception behavior.
• Tested default values, repeated arguments (.append()), and multi-token arguments (nargs).
• Verified independent parsing when the scan type and destination type differ.

Validation

• Focused storage suite: 37 test cases passed, 77 assertions.
• Full suite: 287 test cases passed, 1 skipped, 1,066 assertions passed.
• git diff --check passed.
• Static-analysis and sanitizer tools were unavailable in the development environment.