fix(client/v2): *big.Int unmarshal (cherry-pick #21853) (backport #24361)

[mergify]

Description

Cherry-picks #21853

Steps to reproduce: simd tx protocolpool create-continuous-fund alice 0.1

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Author Checklist

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• included the necessary unit and integration tests

• added a changelog entry to CHANGELOG.md

• updated the relevant documentation or specification, including comments for documenting Go code

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• confirmed the correct type prefix in the PR title
• confirmed all author checklist items have been addressed
• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

Summary by CodeRabbit

• Bug Fixes
  • Resolved an issue with processing large numeric values in transactions.
• New Features
  • Enhanced error messages to display valid option choices for invalid inputs.
  • Added support for precise decimal inputs in command-line flags, improving both validation and handling.

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This is an automatic backport of pull request #24361 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of df07789 has failed:

On branch mergify/bp/release/v0.53.x/pr-24361
Your branch is up to date with 'origin/release/v0.53.x'.

You are currently cherry-picking commit df0778984.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   client/v2/autocli/flag/builder.go
	new file:   client/v2/autocli/flag/legacy_dec.go
	modified:   simapp/go.mod
	modified:   tests/go.mod

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   client/v2/CHANGELOG.md
	both modified:   simapp/go.sum

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally