[GP-02] Add Unit Commitment heuristics

[aoustry]

Affected Component

Optimization problem construction (simulation/)

Type of Change

Major: backward-incompatible change or major new feature (e.g. rolling horizon)

Description

Introduce the possibility of having a 2-stage heuristic for solving of the dispatch problems with integer variables.

• The user should declare inside optim-config.yml the name of the heuristic used for each model. The name of the heuristic refers to a Python method hardcoded in a dedicated submodule of GemsPy.
• The user should declare inside system.yml the integer-strategy: exact (default) | relaxed | heuristic

The code modification should be done "below" the function run_block of session.py, so that the changes directly benefit to run_frontal, run_parallel and run_sequential.

Results Impact

No impact if the integer-strategy is exact. Else, potential impacts.

Validation Strategy

• Parallel run with Legacy Antares Simulator for very simple studies

Process Checklist

Step 1 — Issue Creation

• Issue created and linked to process GP-02

Step 2 — Triage

• Process confirmed applicable
• Assigned to responsible contributor
• Priority and milestone set (if applicable)

Step 3 — Impact Analysis ⚠️ extended results analysis required

• Affected modules identified
• Results impact explicitly stated: change intended / no change intended
• If results expected to change: before/after difference described and justified
• Breaking vs backward-compatible change determined

Step 4 — Implementation

• Code changes implemented
• Backward compatibility maintained unless explicitly intended as breaking

Step 5 — Testing & Validation

• If results expected to change: reference studies updated with new expected values
• If results must not change: solver equivalence confirmed via tests
• Unit tests cover changed components

Step 6 — CI Validation

• Type checking passes (mypy)
• Formatting passes (black, isort)
• All tests pass in CI (pytest)

Step 7 — Review & Merge

• PR reviewed; documentation changes included

Step 8 — Versioning

• pyproject.toml version bumped

Step 9 — Supporting Files

• AGENTS.md reviewed for impact and updated if needed

Step 10 — Release

• If a release is needed: follow the release process in the Developer Guidelines