fix(coin): align fromString denom regex with Cosmos denom spec

[Vritra4]

same with #168

Summary by CodeRabbit

• New Features

  • Enhanced denom validation now accepts additional special characters (colons, slashes, dots, underscores, hyphens).
  • Stricter denom length constraints enforced for better compliance.
  • Improved decimal coin parsing with support for negative amounts.

• Tests

  • Extended test coverage validating denom characters and length bounds.
  • Added comprehensive test scenarios for decimal coin parsing.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 36da4b37-017f-43b9-80b7-8919071b27f9

📥 Commits

Reviewing files that changed from the base of the PR and between 62f6e47 and 5e2169a.

⛔ Files ignored due to path filters (1)

• package-lock.json is excluded by !**/package-lock.json

📒 Files selected for processing (2)

• src/core/coin.ts
• test/unit/core/coin.spec.ts

---

Walkthrough

This PR centralizes coin and denom string validation into shared regex constants, updates parseCoin and parseDecCoin to use those patterns instead of inline regexes, refactors the DecCoin constructor's amount-type handling, and adds comprehensive test coverage for denom character support and length constraints.

Changes

Coin validation module update

Layer / File(s)	Summary
Denom and coin string validation regex constants src/core/coin.ts	Introduces DENOM_REGEX_FRAGMENT, COIN_STRING_REGEX, and DEC_COIN_STRING_REGEX constants that define expanded denom character support (:, /, ., _, -) and enforce Cosmos denom length constraints.
Update parseCoin and parseDecCoin validation src/core/coin.ts	parseCoin and parseDecCoin now validate input against centralized regex patterns, replacing inline regex definitions with the shared constants.
DecCoin constructor input normalization refactoring src/core/coin.ts	Refactors the amount parameter handling from inline case statements into a structured switch statement with multi-line assignments.
Coin validation and parsing test coverage test/unit/core/coin.spec.ts	Extends parseCoin tests to verify denom character support and Cosmos denom length bounds; adds new parseDecCoin test suite covering denom validation, negative amounts, and length constraints.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A coin's true form now clearly defined,
With patterns shared across the line,
Denoms dance with characters new,
Length bounds enforced, validation true,
Tests ensure the parsing's right!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: aligning the denom regex patterns in coin parsing functions with Cosmos specification, which is the central focus of the file modifications.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/v2-denom

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}