feat: add issued_count and redeemed_count to keyset_amounts

[Forte11Cuba]

Description

Add issued_count and redeemed_count columns to the keyset_amounts table to track per-keyset operation counts (number of blind signatures issued and proofs redeemed) alongside the existing amount totals (total_issued, total_redeemed).

These counters are the foundation for the volume-based rotation trigger described in #1999 (Keyset Autorotate & Auto-Prune). They are incremented atomically in the same transaction as the underlying blind_signature insert and proof state update, so they cannot drift under normal operation.

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Notes to the reviewers

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CHANGED

ADDED

• issued_count and redeemed_count columns to keyset_amounts table (SQLite + Postgres migrations with backfill)
• get_total_issued_count method on SignaturesDatabase trait
• get_total_redeemed_count method on ProofsDatabase trait

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)

[codecov]

Codecov Report

❌ Patch coverage is 98.65772% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.84%. Comparing base (f0e028c) to head (98461e6).

Files with missing lines	Patch %	Lines
crates/cdk-sql-common/src/mint/proofs.rs	90.00%	1 Missing ⚠️
crates/cdk-sql-common/src/mint/signatures.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2008      +/-   ##
==========================================
+ Coverage   67.76%   67.84%   +0.07%     
==========================================
  Files         353      353              
  Lines       67840    67989     +149     
==========================================
+ Hits        45975    46130     +155     
+ Misses      21865    21859       -6     

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