Added MPI support for Slurm job submission using two default sbatch templates (MPI and non-MPI)

[pcolt]

It closes #79:

• A sbatch file is now uploaded and used when a new graph is uploaded and evaluated by the backend
• A simple template/replace logic is used with parameters between {{ and }} (i.e. for name of directory where nodes' status are stored)

MPI specific changes:

• Two default sbatch templates (MPI and non-MPI) can be selected depending from the user choice made in Settings
• Added new modal to configure MPI execution (number of nodes, tasks per node and time limit)
• Updated Coral submodule to include new MPI initialization (ref. Coral issue #53) via new plugin key in the uploaded network json file (see file example below)

{
  "plugin": { 
    "MPI": { 
      "enabled": true,
      "max_num_threads": 1
    }
  },
  "workflow": {
    "nodes": {
      "2": {
        "type": "std::string",
        "position": { "x": -247.56635394948717, "y": 375.3717066817897 },
        "value": "laplace-problem",
        "qualified_id": "2"
      },
      "6": {
        "type": "LaplaceProblem::run<2>",
        "position": { "x": 154.32888923688336, "y": 264.52935128677746 },
        "qualified_id": "6"
      },
      "8": {
        "type": "LaplaceProblem<2>",
        "position": { "x": -236.8555047646572, "y": 242.6178965506271 },
        "qualified_id": "8"
      }
    },
    "edges": {
      "0": { "source": 2, "target": 6, "source_output": 0, "target_input": 1 },
      "1": { "source": 8, "target": 6, "source_output": 0, "target_input": 0 }
    }
  },
  "version": 1,
  "author": "dealiix-platform",
  "date_time_utc": "2026-03-16T13:21:09.943Z"
}

Also in this PR:

• Execution nodes' status is now saved in a separated directory nodes-exec-status

• Documentation to inspect and programmatically empty keys from Electron-store store

• Update CHANGELOG