Track S3 legacy naming that now represents object-storage behavior

[AptS-1547]

Context

After the Azure Blob / Tencent COS / OneDrive connector work, several names that still contain s3 now describe broader object-storage behavior. Some of these names are valid and should remain because they are public wire values, historical migration facts, or truly S3-compatible concepts. Others are internal/UI names that now mislead contributors and users.

This issue tracks the naming debt so we can clean it up in safe batches instead of doing a risky global rename.

Keep as-is or change only with a compatibility plan

These names are public contract, migration history, or true S3-compatible driver concepts:

• driver_type = "s3" / DriverType::S3
  • Public wire value and DB enum. Keep.
• s3_upload_strategy / s3_download_strategy
  • Existing StoragePolicyOptions JSON fields. Azure Blob / Tencent COS currently reuse them. Do not rename directly without serde aliasing, DB backfill, OpenAPI/frontend compatibility, and docs.
• s3_path_style
  • Actual S3-compatible path-style concept. Keep.
• S3TempKey / S3MultipartId in old migrations
  • Migration history. Do not rewrite.
• S3Driver, S3Connector, aws_sdk_s3, s3_config, normalize_s3_endpoint_and_bucket
  • Real S3-compatible driver code. Keep.
• RemoteCreateS3IngressProfileRequest
  • Managed follower ingress currently supports local and s3 targets. Keep unless that model expands.

Names that now have broader object-storage meaning

These should be cleaned up gradually with aliases or internal renames:

• S3UploadStrategy / S3DownloadStrategy
  • Defined in src/types/storage_policy.rs.
  • Now used by S3-compatible, Azure Blob, and Tencent COS connector paths.
  • Candidate alias/new name: ObjectStorageUploadStrategy / ObjectStorageDownloadStrategy.
• StorageConnectorCapabilities.s3_transfer_strategy
  • Defined in src/storage/connector_descriptor.rs.
  • Actual meaning is “connector exposes object-storage upload/download strategy options”.
  • Candidate new field: object_storage_transfer_strategy, keeping s3_transfer_strategy for compatibility for at least one release.
• StorageConnectorUploadTransport::ObjectStorage(S3UploadStrategy)
  • Defined in src/storage/connectors/upload.rs.
  • Outer enum is already object-storage scoped; inner enum name is too narrow.
• effective_s3_upload_strategy() / effective_s3_download_strategy()
  • Defined in src/types/storage_policy.rs.
  • Add effective_object_storage_upload_strategy() / effective_object_storage_download_strategy() and migrate call sites.
• s3_part_number
  • Used in src/services/upload_service/chunk.rs.
  • Multipart part numbering is now object-storage / remote multipart behavior.
  • Candidate name: object_part_number.
• S3_PROCESSING_PROGRESS
  • Used in frontend-panel/src/components/files/uploadResume.ts.
  • It is just upload finalization/progress scaling, not S3-specific.
  • Candidate name: SERVER_FINALIZE_PROGRESS or REMOTE_PROCESSING_PROGRESS.
• Frontend component/function names:
  • S3UploadStrategyField
  • S3DownloadStrategyField
  • S3ConnectionFields where used for generic object-storage descriptors
  • supportsS3TransferStrategy
  • normalizeS3ConnectionFields where used outside true S3-compatible profile handling
• Frontend i18n display strings:
  • s3_upload_strategy: currently “S3 Upload Strategy” / “S3 上传方式”
  • s3_download_strategy: currently “S3 Download Strategy” / “S3 下载方式”
  • These labels are confusing when the selected connector is Azure Blob or Tencent COS. The key can stay initially, but displayed copy should say “Object Storage Upload Strategy” / “对象存储上传方式”.

Suggested migration plan

Batch 1: low-risk internal/UI cleanup

• Rename S3_PROCESSING_PROGRESS to a provider-neutral name.
• Change UI labels for s3_upload_strategy / s3_download_strategy to object-storage wording without changing the JSON keys.
• Add supportsObjectStorageTransferStrategy() as the preferred predicate and keep supportsS3TransferStrategy() as a temporary alias.
• Add provider-neutral component names for upload/download strategy fields, keeping the wire field names unchanged.
• Rename local variables like s3_part_number to object_part_number where no public API is affected.

Batch 2: Rust aliases/helpers

• Add type aliases or new internal names:
  • ObjectStorageUploadStrategy
  • ObjectStorageDownloadStrategy
• Add helper methods:
  • effective_object_storage_upload_strategy()
  • effective_object_storage_download_strategy()
• Move connector/upload-service call sites to the object-storage helper names while keeping serialized fields unchanged.

Batch 3: descriptor/API compatibility work, if we still want it

• Add object_storage_transfer_strategy to connector descriptor output.
• Keep s3_transfer_strategy for generated clients and existing frontend code during a compatibility window.
• Update OpenAPI, generated frontend types, and descriptor tests.

Do not do casually

• Do not directly rename s3_upload_strategy / s3_download_strategy in persisted policy JSON without a proper migration and serde compatibility story.
• Do not rename driver_type = "s3"; this is still the correct S3-compatible driver type.
• Do not rewrite old migration enum names just to make them pretty.

Search notes

The main places found during the audit:

• src/types/storage_policy.rs
• src/storage/connector_descriptor.rs
• src/storage/connectors/upload.rs
• src/storage/connectors/{s3,azure_blob,tencent_cos}.rs
• src/services/upload_service/chunk.rs
• frontend-panel/src/components/files/uploadResume.ts
• frontend-panel/src/components/admin/storage-policy-dialog/*S3*
• frontend-panel/src/components/admin/storage-policy-dialog/descriptorPredicates.ts
• frontend-panel/src/i18n/locales/{zh,en}/admin/policies.json
• developer-docs/** and docs/** where user-facing wording should distinguish S3-compatible from general object storage

Acceptance criteria

• New internal code uses object-storage naming for behavior shared by S3-compatible, Azure Blob, and Tencent COS.
• Public wire fields remain backward compatible.
• Admin UI does not label Azure Blob / Tencent COS transfer settings as “S3 upload/download strategy”.
• Tests cover compatibility for existing s3_upload_strategy / s3_download_strategy policy JSON.