feat(files): enforce workflow-scoped file transfers

[v1r3n]

Pull Request type

• Bugfix
• Feature
• Refactoring (no functional changes, no api changes)
• Build related changes
• WHOSUSING.md
• Other (please describe):

Changes in this PR

Makes file operations workflow-aware end to end:

• scopes upload URL refresh, completion, metadata, and multipart routes by workflow ID
• requires the exact owning workflow for upload mutations
• allows workflow-family access for metadata and downloads
• adds best-effort multipart abort, including native S3 abort
• returns the storage-reported fileSize in metadata
• updates REST, service, integration, and E2E coverage
• replaces stale file-storage API/architecture/Java SDK documentation

Breaking change: the previous unscoped mutation and metadata routes are removed. Clients must pass workflow context on every operation.

Issue #

Tests

• ./gradlew :conductor-core:test --tests org.conductoross.conductor.core.storage.converter.FileModelConverterTest --tests org.conductoross.conductor.core.storage.FileStorageServiceImplTest :conductor-rest:test --tests org.conductoross.conductor.rest.controllers.FileResourceTest -x :conductor-ai:compileJava
• ./gradlew :conductor-common:spotlessJavaApply :conductor-core:spotlessJavaApply :conductor-rest:spotlessJavaApply :conductor-awss3-storage:spotlessJavaApply :conductor-e2e:spotlessJavaApply :conductor-test-harness:spotlessJavaApply
• live local-storage E2E on port 8080: media-transcode workflow completed and metadata returned correct byte sizes

Alternatives considered

Keeping unscoped routes or trusting a supplied file handle alone would leave upload mutations detached from ownership. Proxying file bytes through Conductor was also rejected; signed URLs retain the direct-to-storage data path.

[v1r3n]

Companion Java SDK PR: conductor-oss/java-sdk#137. The SDK PR consumes the workflow-scoped routes introduced here and documents the coordinated migration.