Implement Cluster Scan

[currantw]

Implement Cluster Scan

Overview

Adds ScanAsync methods to the standalone and cluster clients.

Key Changes

• Added ScanAsync to IGenericClusterCommands and implemented it in GlideClusterClient, which calls new BaseClient.ClusterScanCommand method.
• Added ScanAsync to IGenericCommands (standalone client) and implemented it in GlideClusterClient, which calls the existing Glide SCAN command. Provides consistent scan interface for standalone and cluster clients.
• Cluster scan is implemented with ClusterScanCursor, while both standalone and cluster scanning use ScanOptions, which supports match pattern, count, and type arguments. Refactor existing Request.GenericCommands.ScanAsync and KeysAsync method to use ScanOptions.
• Added RequestClusterScanFfi and RemoveClusterScanCursorFfi methods to "FFI.methods.rs", as well as Add request_cluster_scan and remove_cluster_scan_cursor to "rust/src/lib.rs" that call into the existing core methods (implementation based on equivalent methods here).

Testing Coverage

• Added new ScanTests for both standalone and cluster ScanAsync methods.
• Updated CommandTests for change to internal Request.ScanAsync interface.

Breaking Changes

None.

[Copilot]

Pull Request Overview

This PR implements cluster and standalone scan functionality for the Valkey GLIDE client. The changes introduce a consistent ScanAsync API across both client types while adding support for filtering by pattern, type, and count options.

Key Changes:

• Added ScanAsync methods to IGenericCommands (standalone) and IGenericClusterCommands (cluster) interfaces with implementations in respective clients
• Introduced ScanOptions class supporting match pattern, count, and type filtering, and ClusterScanCursor for cluster scan state management
• Refactored internal Request.ScanAsync to use ScanOptions instead of individual parameters, updating cursor handling from long to string

Reviewed Changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/Valkey.Glide.UnitTests/CommandTests.cs	Updated unit tests to use new ScanAsync signature with ScanOptions and string cursors
tests/Valkey.Glide.IntegrationTests/ScanTests.cs	Added comprehensive integration tests for scan functionality with filtering options
sources/Valkey.Glide/abstract_APITypes/ClusterScanCursor.cs	New cursor abstraction for cluster scan operations
sources/Valkey.Glide/Internals/Request.GenericCommands.cs	Refactored scan command builder to accept ScanOptions and return string cursors
sources/Valkey.Glide/Internals/FFI.methods.cs	Added FFI bindings for cluster scan operations
sources/Valkey.Glide/GlideClusterClient.cs	Implemented ScanAsync for cluster client using new cluster scan command
sources/Valkey.Glide/GlideClient.cs	Implemented ScanAsync for standalone client and updated KeysAsync to use new scan interface
sources/Valkey.Glide/Commands/Options/ScanOptions.cs	New options class for scan configuration
sources/Valkey.Glide/Commands/IGenericCommands.cs	Added ScanAsync method signature for standalone client
sources/Valkey.Glide/Commands/IGenericClusterCommands.cs	Added ScanAsync method signature for cluster client
sources/Valkey.Glide/Commands/Constants/Constants.cs	Added TYPE keyword constant
sources/Valkey.Glide/BaseClient.cs	Added ClusterScanCommand implementation and relocated server version fields
rust/src/lib.rs	Implemented Rust FFI functions for cluster scan operations

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