Add GetQuoteTtl Method to Management RPC

[KvngMikey]

FIXES #787

SUMMARY

Adds a GetQuoteTtl method to the mint management RPC, allowing operators to retrieve the expiry(ttl) timestamp for a specific mint or melt quote.

Previously, quote TTLs could be updated via UpdateQuoteTtl, but there was no way to query the active values beforehand. This enables operational inspection of quote lifetime without querying the HTTP API or directly accessing the database.

Changes

• Extend management.proto with:

  • GetQuoteTtlRequest { quote_id }

  • GetQuoteTtlResponse { expiry }

• Regenerate gRPC Python bindings

• Implement GetQuoteTtl handler in management_rpc.py

  • Looks up the quote by ID

  • For mint_quote expiry is not stored, decode Bolt11 invoice and compute expiry, otherwise lookup melt_quote and return stored expiry.

  • Returns NotFound if the quote does not exist

Manual Verification:

• start the mint
• create a mint quote.
• copy the quoteId and query the getQuoteTTL with that ID.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 64 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.02%. Comparing base (8748b99) to head (cc8b824).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
cashu/mint/management_rpc/protos/management_pb2.py	0.00%	35 Missing ⚠️
cashu/mint/management_rpc/management_rpc.py	0.00%	21 Missing ⚠️
.../mint/management_rpc/protos/management_pb2_grpc.py	0.00%	8 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #874       +/-   ##
===========================================
+ Coverage   50.02%   63.02%   +12.99%     
===========================================
  Files          89       89               
  Lines       10545    10625       +80     
===========================================
+ Hits         5275     6696     +1421     
+ Misses       5270     3929     -1341     

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[KvngMikey]

@callebtc - this is also ready...

cc @a1denvalu3