Let Context.redefine parse magnitudes with the registry's non_int_type

[apoorva-01]

Closes #2301

• Executed pre-commit run --all-files
• Covered by unit tests
• Documented in docs/
• Added a CHANGES entry

Context.redefine always parsed the definition with ParserConfig(float), so redefining a unit on a non_int_type=decimal.Decimal registry produced a float scale and conversion blew up with TypeError: unsupported operand type(s) for ** or pow(): 'float' and 'decimal.Decimal'.

I added a non_int_type argument (default float) so the redefinition can be parsed with the registry's type — option 1 from the discussion, matching Context.from_lines.

One thing to note: it's opt-in, so the caller passes non_int_type=decimal.Decimal; it doesn't auto-inherit from the registry. If you'd rather it inherit, I can move the parsing into add_context instead — happy to switch.

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 448 untouched benchmarks
⏩ 448 skipped benchmarks¹

---

_{Comparing apoorva-01:fix/2301-context-redefine-non-int-type (4a45497) with master (7a927b4)}

Footnotes

1. 448 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩