fix: Operational Certificate circular dependency in KES signature

[jpraynaud]

Content

This PR includes a fix for the circular dependency of the Operational Certificate in the context of KES signature:

• Removed the usage of Operational certificate from ChainObserver trait KES period computation function.
• Adapted the implementations of the ChainObserver trait.
• Adapted the KES signature in the DMQ message builder.

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
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  • Useful pull request description
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Issue(s)

Closes #2668

[github-actions]

Test Results

    4 files  ±0    158 suites  ±0   22m 54s ⏱️ +5s
2 152 tests ±0  2 152 ✅ ±0  0 💤 ±0  0 ❌ ±0 
6 602 runs  ±0  6 602 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 3d8b215. ± Comparison against base commit 7ec438a.

♻️ This comment has been updated with latest results.

[Copilot]

Pull Request Overview

This PR fixes a circular dependency in the KES signature process by removing the requirement for an operational certificate parameter from the ChainObserver trait's get_current_kes_period method. Instead of relying on the operational certificate for KES period computation, the implementation now calculates the current KES period directly from the current slot and a hardcoded slots-per-KES-period value.

• Removed OpCert parameter from get_current_kes_period method signature across all ChainObserver implementations
• Updated CLI observer to calculate KES period from current slot instead of querying operational certificate info
• Modified callers to use the parameterless method and compute relative KES periods locally

Reviewed Changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
mithril-signer/src/runtime/runner.rs	Updated to call parameterless get_current_kes_period() method
mithril-signer/src/dependency_injection/builder.rs	Added operational certificate path to chain observer configuration
mithril-aggregator/src/services/signer_registration/verifier.rs	Updated to call parameterless get_current_kes_period() method
internal/mithril-dmq/src/message.rs	Updated to call parameterless get_current_kes_period() method
internal/cardano-node/mithril-cardano-node-chain/src/chain_observer/interface.rs	Updated trait definition to remove OpCert parameter
internal/cardano-node/mithril-cardano-node-chain/src/chain_observer/cli_observer.rs	Refactored to calculate KES period from slot number instead of operational certificate
internal/cardano-node/mithril-cardano-node-chain/src/chain_observer/pallas_observer.rs	Updated implementation to match new interface
Various Cargo.toml files	Version bumps for affected crates
Test files	Updated mocks and test implementations to match new interface

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