* fix(cdk): prevent duplicate blinded message processing with database constraints
Add unique constraints on blinded_message column in both PostgreSQL and SQLite databases, and implement application-level checks to prevent duplicate blinded messages from being processed. Also ensure proper cleanup of melt requests after successful processing.
* feat: db tests for unique
* refactor(cdk-sql): consolidate blinded messages into blind signature table
Migrate from separate blinded_messages table to unified blind_signature table.
Add signed_time column and make c column nullable to track both pending
blind messages (c=NULL) and completed signatures. Update insert/update
logic to handle upsert scenarios for blind signature completion.
* refactor(cdk-sql): remove unique constraint migration and filter queries for signed messages
Remove database-level unique constraint on blinded_message and instead filter
queries to only consider messages with signatures (c IS NOT NULL
* refactor(database): improve blinded message duplicate detection using database constraints
Replace manual duplicate checking with database constraint handling for better
reliability and simplified code flow in melt request processing.
* refactor(cdk-sql): optimize blind signature processing with batch queries
Replace individual queries per blinded message with single batch query
and HashMap lookup to eliminate N+1 query performance issue.
* fix: signed time to swap sigs
* refactor(cdk): split blinded message handling and improve duplicate detection
- Split add_melt_request_and_blinded_messages into separate methods
- Add blinded messages to database before signing in swap operations
- Improve duplicate output detection with proper error handling
- Make add_blinded_messages method accept optional quote_id for flexibility
* refactor(cdk): add BlindedMessageWriter for improved transaction rollback
- Add BlindedMessageWriter component for managing blinded message state
- Implement proper rollback mechanisms in swap operations
- Add delete_blinded_messages database interface for cleanup
- Improve error handling with better state management
