* feat(cdk): add generic key-value store functionality for mint databases
Implements a comprehensive KV store system with transaction support,
namespace-based organization, and validation for mint databases.
- Add KVStoreDatabase and KVStoreTransaction traits for generic storage
- Include namespace and key validation with ASCII character restrictions
- Add database migrations for kv_store table in SQLite and PostgreSQL
- Implement comprehensive test suite for KV store functionality
- Integrate KV store traits into existing Database and Transaction bounds
* feat: add LDK Node Lightning backend with comprehensive integration
- Add new cdk-ldk-node crate implementing Lightning backend using LDK Node
- Extend MintPayment trait with start/stop methods for processor lifecycle management
- Add LDK Node configuration support to cdk-mintd with chain source and gossip options
- Enhance mint startup/shutdown to properly manage payment processor lifecycle
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Co-authored-by: Erik <78821053+swedishfrenchpress@users.noreply.github.com>
* refactor(cdk-lnbits): migrate to LNbits v1 websocket API and remove webhook support
- Remove webhook-based payment notifications in favor of v1 websocket API
- Add explicit documentation that only LNbits v1 API is supported
- Remove webhook_url parameter and related router setup code
- Simplify payment status handling by removing pending status logic
- Switch to local lnbits-rs dependency for development
- Remove unused axum dependency and clean up imports
- Update configuration documentation and examples
* refactor(cdk-lnbits): extract payment processing logic into helper methods
Improve code readability by separating message processing, payment response
creation, and payment hash decoding into dedicated methods. This reduces
complexity in the main payment waiting loop while maintaining identical
functionality
* chore: bump lnbits-rs
