Do not use epoch for sorting

[roman-khimov]

No description provided.

[Copilot]

Pull Request Overview

This PR removes the use of epoch-based fields for sorting and replaces them with the creation timestamp across several API layers.

• Removed all references to CreationEpoch and its associated attributes from data structures and search filters.
• Updated parsing, error messages, and sorting functions to rely solely on CreationTimestamp.
• Modified tests and mocks to use a controlled current time for consistency.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
api/layer/tagging.go	Removed CreationEpoch field and updated parsing and sorting to use CreationTimestamp.
api/layer/system_object.go	Replaced CreationEpoch with CreationTimestamp and adjusted attribute indexes and error logs.
api/layer/object.go	Updated attribute mappings and sort functions to use CreationTimestamp consistently.
api/layer/neofs_mock.go	Introduced currentTime for mock objects and deliberately ignored prm.CreationTime.
api/layer/layer.go	Changed container versioning logic to use CreationTimestamp over CreationEpoch.

Comments suppressed due to low confidence (3)

api/layer/neofs_mock.go:61

• [nitpick] Consider adding a comment clarifying why prm.CreationTime is deliberately ignored in favor of t.currentTime to aid future maintainers.

t.currentTime: time.Now().Unix(),

api/layer/tagging.go:130

• Ensure that replacing CreationEpoch with CreationTimestamp is consistently propagated; verify that downstream logic and documentation are updated to reflect this change.

psr.CreationTimestamp, err = strconv.ParseInt(item.Attributes[1], 10, 64)

api/layer/object.go:466

• Double-check that the attribute index mapping correctly corresponds to the new CreationTimestamp field, ensuring no misalignment with the upstream attribute order.

psr.CreationTimestamp, err = strconv.ParseInt(item.Attributes[1], 10, 64)