[Session] Ensure deterministic supplier set for historical sessions

[red-0ne]

Objective

Ensure that queries for past Sessions return a consistent set of Suppliers, regardless of Supplier turnover (i.e., staking/unstaking).

Origin Document

When hydrating a Session, the current logic always selects from the currently staked Suppliers.

This approach is problematic in the context of claim settlement, which occurs after the corresponding session has ended. At that point, the new Supplier set may not match the one used when serving the now-settling Session.

Goals

• Ensure a deterministic set of Suppliers for a given Session, regardless of when the Session is queried.

Deliverables

• A single PR addressing the issue by filtering Suppliers based on the query height.

Non-goals / Non-deliverables

• Implementing historical state persistence
• Persisting the Supplier set beyond the claim settlement height

General deliverables

• Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• Testing: Add new tests (unit and/or E2E) to the test suite.
• Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

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Creator: @Red0ne
Co-Owners: @bryanchriswhite