Validate filesystem storage paths

[andrew]

Summary

• validate filesystem storage object paths before joining them under the storage root
• reject traversal, absolute, malformed slash, empty, and backslash paths across filesystem operations
• preserve empty-prefix listing behavior for ListPrefix

Testing

• go test ./internal/storage
• go test ./...

Addresses CodeQL alerts for uncontrolled data used in path expressions in internal/storage/filesystem.go.

[Copilot]

Pull request overview

This PR hardens internal/storage’s filesystem-backed storage by validating object paths before joining them under the storage root, preventing path traversal/absolute-path issues while keeping ListPrefix("") behavior intact.

Changes:

• Introduce cleanStoragePath validation and route all filesystem operations through it via fullPath.
• Add prefixPath to preserve empty-prefix listing semantics for ListPrefix.
• Expand tests to cover rejection of absolute, traversal, malformed slash/dot-segment, empty, and backslash-containing paths.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
internal/storage/filesystem.go	Adds centralized storage-path validation and special-cases empty prefix handling for ListPrefix.
internal/storage/filesystem_test.go	Expands invalid-path coverage and adds a dedicated test for empty-prefix listing behavior.

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