fix(signer): respect allow_all_sighashes in SignerWrapper::sign_input

[muhahahmad68]

Description

SignOptions::allow_all_sighashes is documented as controlling whether the signer will accept non-SIGHASH_ALL sighash types. However, the check only existed inside Wallet::sign as a PSBT-wide pre-flight guard. The underlying SignerWrapper<PrivateKey>::sign_input never consulted it, meaning callers using InputSigner or TransactionSigner directly could bypass the check entirely.

Added a sighash guard in SignerWrapper<PrivateKey>::sign_input before the match self.ctx dispatch. This ensures the check covers all signing contexts (Legacy, Segwitv0, Taproot) and all delegating implementations in a single place.

Tests Added

• Taproot input with SIGHASH_NONE and allow_all_sighashes: false returns NonStandardSighash
• Same setup with allow_all_sighashes: true passes the guard successfully

Fixes #469

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran just p before pushing

New Features:

• N/A

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 80.33%. Comparing base (a9ad3b9) to head (9e45c56).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
src/wallet/signer.rs	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #476      +/-   ##
==========================================
+ Coverage   80.05%   80.33%   +0.27%     
==========================================
  Files          24       24              
  Lines        5360     5430      +70     
  Branches      244      248       +4     
==========================================
+ Hits         4291     4362      +71     
  Misses        990      990              
+ Partials       79       78       -1     

Flag	Coverage Δ
rust	80.33% <92.30%> (+0.27%)	⬆️

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[muhahahmad68]

Makes more sense, I'll effect the changes as suggested. Much thanks @benthecarman

[aagbotemi]

Well done working on this @muhahahmad68. I left some reviews for you.

[ValuedMammal]

ACK 9e45c56; ran the tests locally