[docstring][error] Fixes raises: sections in docstrings across codebase to show correct error types

[forfudan]

This PR updates docstring Raises: sections across Decimo to replace generic Error entries with specific error types (e.g., ValueError, OverflowError, ZeroDivisionError, ConversionError) so API documentation more accurately reflects runtime behavior.

Changes:

• Standardized and expanded docstring Raises: sections across TOML parsing, numeric parsing, and multiple numeric types (Decimal128/Big*).
• Replaced generic Error/DecimoError docstring entries with concrete error types used by the implementation.
• Added missing Raises: sections to several functions that previously had none.

[Copilot]

Pull request overview

This PR updates docstring Raises: sections across Decimo to replace generic Error entries with specific error types (e.g., ValueError, OverflowError, ZeroDivisionError, ConversionError) so API documentation more accurately reflects runtime behavior.

Changes:

• Standardized and expanded docstring Raises: sections across TOML parsing, numeric parsing, and multiple numeric types (Decimal128/Big*).
• Replaced generic Error/DecimoError docstring entries with concrete error types used by the implementation.
• Added missing Raises: sections to several functions that previously had none.

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/decimo/toml/parser.mojo	Adds/clarifies Raises: ValueError in parser helpers and header/key parsing routines.
src/decimo/tests.mojo	Documents ValueError raised by TOML test helper parse_file().
src/decimo/str.mojo	Documents ValueError for malformed numeric strings in parse_numeric_string().
src/decimo/decimal128/special.mojo	Documents ValueError/OverflowError for factorial helpers.
src/decimo/decimal128/rounding.mojo	Documents OverflowError for rounding overflow cases.
src/decimo/decimal128/exponential.mojo	Rewrites Raises: for power/root/log/exp functions to specific error types.
src/decimo/decimal128/decimal128.mojo	Updates constructor/conversion docstrings to reflect ConversionError, ValueError, OverflowError.
src/decimo/decimal128/constants.mojo	Documents ValueError for invalid constant selector inputs.
src/decimo/decimal128/arithmetics.mojo	Documents OverflowError/ZeroDivisionError for arithmetic operations.
src/decimo/biguint/biguint.mojo	Updates conversion/operator docstrings to specific overflow/conversion error types.
src/decimo/biguint/arithmetics.mojo	Documents ZeroDivisionError/OverflowError/ValueError in arithmetic helpers.
src/decimo/bigint10/bigint10.mojo	Adds/updates Raises: for parsing/conversion and arithmetic wrapper methods.
src/decimo/bigint10/arithmetics.mojo	Documents ZeroDivisionError for division/modulo operations.
src/decimo/bigint/number_theory.mojo	Documents ValueError for invalid modular arithmetic inputs.
src/decimo/bigint/exponential.mojo	Documents ValueError for invalid sqrt/isqrt inputs.
src/decimo/bigint/bigint.mojo	Updates string/overflow/division/power docstrings with more specific error types.
src/decimo/bigint/arithmetics.mojo	Documents ZeroDivisionError and ValueError in division/power helpers.
src/decimo/bigfloat/bigfloat.mojo	Documents RuntimeError/ConversionError for MPFR-backed operations.
src/decimo/bigdecimal/trigonometric.mojo	Documents ValueError for undefined trig reciprocal cases.
src/decimo/bigdecimal/exponential.mojo	Updates power/root/log/exp docstrings with specific error types.
src/decimo/bigdecimal/constants.mojo	Documents ValueError on invalid precision for constants.
src/decimo/bigdecimal/bigdecimal.mojo	Documents conversion-related ValueError/ConversionError cases.
src/decimo/bigdecimal/arithmetics.mojo	Documents ZeroDivisionError for division/modulo functions.

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