fix(nut17): decode notification payloads with subscription kind

[thesimplekid]

NUT-17 notification payloads are ambiguous without the subscription kind. Quote response shapes overlap and tolerate unknown fields, so shape-based decoding can select the wrong payload variant.

Add a kind-aware payload decoder and use it in the wallet subscription client while preserving the existing generic payload deserialization surface for backports.

This prevents onchain and custom quote notifications from being decoded as the wrong payload variant.

Description

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Notes to the reviewers

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Suggested CHANGELOG Updates

CHANGED

ADDED

REMOVED

FIXED

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Checklist

• I followed the code style guidelines
• I ran just quick-check before committing
• If the Wallet API was modified (added/removed/changed), I have reflected those changes in the FFI bindings (crates/cdk-ffi)

[thesimplekid]

@cdk-bot review

[codecov]

Codecov Report

❌ Patch coverage is 96.18321% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.93%. Comparing base (10cab2a) to head (419878e).

Files with missing lines	Patch %	Lines
crates/cashu/src/nuts/nut17/mod.rs	95.81%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2210      +/-   ##
==========================================
- Coverage   72.95%   72.93%   -0.02%     
==========================================
  Files         359      359              
  Lines       79276    79452     +176     
==========================================
+ Hits        57834    57952     +118     
- Misses      21442    21500      +58     

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[cdk-bot]

Verified findings approved for disclosure:

• Kind-aware notification decoding rejects case-insensitive PaymentMethod values (low) - A notification payload with a semantically matching but non-lowercase standard method, such as "BOLT11" for a bolt11_mint_quote subscription, is rejected before PaymentMethod can normalize it. In the wallet subscription stream this parsing error is propagated, terminating message processing for that stream.
  Additional locations included in summary:
  • crates/cashu/src/nuts/nut17/mod.rs:318

[thesimplekid]

@cdk-bot review

[cdk-bot]

Backport failed for v0.17.x, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin v0.17.x
git worktree add -d .worktree/backport-2210-to-v0.17.x origin/v0.17.x
cd .worktree/backport-2210-to-v0.17.x
git switch --create backport-2210-to-v0.17.x
git cherry-pick -x ba17883082b80be99b293c1bf4537533aa915ecd