Refactor credential types to support multiple cloud storage backends

[sfc-gh-pczajka]

Summary

• Replace S3-only Credentials struct with CloudCredentials enum supporting S3 and GCS at the type level
• Add LocationType enum and extend StageInfo with presigned_url field
• Update query response parsing to build credentials based on locationType from server
• GCS and Azure operations return UnsupportedStorageType error (implementation in follow-up PR)

Part 1 of 2 — type system refactoring only, no new cloud backend functionality.

Test plan

• All 251 sf_core unit tests pass
• All 32 Python e2e put/get tests pass (S3 regression)
• Pre-commit hooks pass (rustfmt, clippy, cargo check)

🤖 Generated with Claude Code

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[Copilot]

Pull request overview

Refactors Snowflake stage credential handling in sf_core to support multiple cloud storage backends by introducing typed location/credential variants and updating query-response parsing and file-transfer entry points accordingly.

Changes:

• Added LocationType and CloudCredentials to represent cloud backends and credentials at the type level.
• Extended StageInfo with location_type and presigned_url, and updated Snowflake query response parsing to populate them.
• Updated upload/download dispatch to branch by location_type, returning UnsupportedStorageType for non-S3 backends (for now).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
sf_core/src/rest/snowflake/query_response.rs	Parses locationType/presignedUrl and builds typed file_manager::StageInfo credentials based on backend.
sf_core/src/file_manager/types.rs	Introduces LocationType, CloudCredentials, and extends StageInfo to carry backend + optional presigned URL.
sf_core/src/file_manager/mod.rs	Routes upload/download by location_type and adds UnsupportedStorageType error variant.
sf_core/src/file_manager/file_transfer.rs	Updates S3 client creation to pull credentials from the CloudCredentials enum.

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[sfc-gh-pczajka]

• Add cloud provider to testing matrix for Python and ODBC #587
• Add GCS file transfer support for download and upload #585
• Refactor credential types to support multiple cloud storage backends #584 👈 (View in Graphite)
• main

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[Copilot]

Pull request overview

Refactors Snowflake file-transfer stage metadata and credential modeling so the type system can represent multiple cloud storage backends (S3 today, GCS/Azure as stubs), and wires the new enums through query response parsing and the file manager.

Changes:

• Introduces LocationType and CloudCredentials (S3/GCS) and extends StageInfo with location_type and presigned_url.
• Updates query response parsing to derive file_manager::StageInfo based on locationType and construct backend-specific credentials.
• Updates S3 transfer code to consume CloudCredentials::S3 and adds explicit “missing S3 credentials” errors.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
sf_core/src/rest/snowflake/query_response.rs	Parses locationType/presignedUrl and constructs backend-specific StageInfo + credentials.
sf_core/src/file_manager/types.rs	Adds LocationType, CloudCredentials, and new StageInfo fields to represent multiple backends.
sf_core/src/file_manager/s3_transfer.rs	Refactors S3 transfer to require S3 credentials variant and improves Snafu context usage.
sf_core/src/file_manager/mod.rs	Routes upload/download by LocationType, returning unsupported errors for non-S3 backends.

Comments suppressed due to low confidence (2)

sf_core/src/file_manager/s3_transfer.rs:180

• create_s3_client matches on stage_info.creds by value, which moves the enum out of a borrowed &StageInfo and should not compile. Match on a reference instead (e.g., match &stage_info.creds { CloudCredentials::S3 { ... } => ... }) or destructure via let CloudCredentials::S3 { .. } = &stage_info.creds to avoid moving.
  sf_core/src/file_manager/s3_transfer.rs:228
• The From<S3CredentialError> impls construct MissingS3Credentials with Location::default(), which loses the actual call-site #[snafu(implicit)] location and makes diagnostics much less useful. Prefer returning UploadFileError/DownloadFileError directly from create_s3_client (or use a Snafu context helper) so the implicit Location is captured at the point of failure.