Port Modelica plugin to fz framework

[Copilot]

Migrates the legacy Java-based Modelica plugin to the Python-based fz framework structure, following the pattern established by other fz model plugins.

Changes

Core Plugin Structure

• .fz/models/Modelica.json - Model definition with variable prefix $, delimiter {}, and CSV output parsing via pandas
• .fz/calculators/Modelica.sh - Execution script with enhanced directory/multi-file handling (previously single-file only)
• .fz/calculators/localhost.json - Calculator configuration mapping model to execution script

Configuration Migration

Old .ioplugin DSL → JSON configuration:

• variableStartSymbol → varprefix
• variableLimit → delim
• Custom output DSL (>> operators) → Shell commands with Python/pandas
• Variable syntax remains ${var~default} (backward compatible)

Documentation & Examples

• README.md - Installation, usage, API reference
• MIGRATION.md - Old vs new plugin comparison, upgrade path
• INSTALL_OPENMODELICA.md - Platform-specific omc installation
• examples/ - Single case, parametric study, cache usage demonstrations
• tests/verify_installation.py - Automated structure validation

Sample Model

model NewtonCooling "An example of Newton's law of cooling"
  parameter Real h=${convection~0.7} "Convective cooling coefficient";
  ...
end NewtonCooling;

Usage:

import fz

results = fz.fzr(
    "samples/NewtonCooling.mo",
    {"convection": [0.1, 0.3, 0.5, 0.7, 0.9]},
    "Modelica",
    calculators="localhost",
    results_dir="results"
)

CI/CD

GitHub Actions workflow validates JSON files, shell syntax, and directory structure on push/PR.

Original prompt

Create a repository porting old modelica plugin (https://github.com/Funz/plugin-modelica) to new fz. See https://github.com/Funz/fz to get details of new fz "model" plugins (mostly files in .fz/models/... and .fz/calculators/...)

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