feat: Add Universal AppImage builder for multi-distro eSim packaging

appimage/.gitignore

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+build-eSim-AppImage/
+*.AppImage
+*.zip

appimage/README.md

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+# eSim Universal AppImage Builder
+
+[![Build Status](https://img.shields.io/badge/build-automated-success.svg)](https://github.com/mahakgupta0123/eSim_Universal_packagemanager_linux)
+[![Platform](https://img.shields.io/badge/platform-Linux%20x86__64-blue.svg)](https://www.linux.org/)
+[![License](https://img.shields.io/badge/License-GPL%20v3-red.svg)](https://www.gnu.org/licenses/gpl-3.0)
+[![Distros](https://img.shields.io/badge/distros-Ubuntu%20%7C%20Fedora%20%7C%20Arch%20%7C%20openSUSE-orange.svg)](#-supported-distributions)
+
+A comprehensive, automated build system for creating a **Universal AppImage** of [eSim](https://esim.fossee.in/) — an open-source EDA tool for circuit design, simulation, analysis, and PCB design developed by the [FOSSEE](https://fossee.in/) initiative at IIT Bombay.
+
+This project solves the "dependency hell" problem on Linux by bundling eSim and all its complex requirements into a **single, portable executable** that works across virtually all modern Linux distributions — no installation required.
+
+---
+
+## 🚀 Key Features
+
+- **True Multi-Distro Compatibility** — Automatically detects and handles dependencies for:
+  - **Ubuntu / Debian / Linux Mint** (`apt`)
+  - **Fedora / RHEL / CentOS** (`dnf` / `yum`)
+  - **Arch Linux / Manjaro** (`pacman`)
+  - **openSUSE** (`zypper`)
+
+- **Bundled Tool Suite**:
+  - **eSim 2.5** — Latest stable EDA suite with schematic capture, simulation, and PCB design
+  - **KiCad 6.0.11** — Bundled via AppImage for perfect compatibility and isolation
+  - **NgSpice 35** — Custom-built from source with specialized patches for NGHDL/GHDL integration, clean termination, and Arch compatibility
+  - **OpenModelica / OMEdit** — Modelica-based modeling and simulation environment
+  - **GHDL** — Open-source VHDL simulator for NGHDL digital models
+  - **Verilator** — Fast Verilog HDL simulator for NgVeri integration
+  - **Makerchip** — Built-in support for Makerchip IDE integration
+
+- **Zero Configuration** — Automatically sets up Python virtual environments, GTK resources, library paths, and runtime dependencies inside the AppImage
+
+- **Cross-Distribution Library Bundling** — Intelligent fallback system that downloads Ubuntu `.deb` packages for libraries not available on non-Ubuntu systems (OpenSceneGraph, Qt5WebKit, ICU, omniORB)
+
+---
+
+## 📋 Prerequisites
+
+Before running the builder, ensure you have:
+
+1. **A Linux machine** (x86_64 architecture)
+2. **Sudo privileges** (for installing build tools like `gcc`, `wget`, `python3`, etc.)
+3. **Internet connection** — The script downloads several hundred MB of sources and tools
+4. **Disk space** — At least **5 GB** of free space for the build process
+5. **Basic build tools** — The script will install anything missing, but having `git`, `gcc`, and `wget` pre-installed speeds things up
+
+---
+
+## 🛠️ Build Instructions
+
+Creating your universal AppImage is as simple as running one command:
+
+### 1. Clone the Repository
+```bash
+git clone https://github.com/mahakgupta0123/eSim_Universal_packagemanager_linux.git
+cd eSim_Universal_packagemanager_linux
+```
+
+### 2. Make the Script Executable
+```bash
+chmod +x build-appimage.sh
+```
+
+### 3. Run the Builder
+```bash
+./build-appimage.sh
+```
+
+The script proceeds through **10 automated stages**:
+
+| Stage | Description |
+|-------|-------------|
+| 1 | Distribution detection & system checks |
+| 2 | Prerequisite & dependency installation |
+| 3 | Tool downloading (KiCad AppImage, OpenModelica, etc.) |
+| 4 | eSim source preparation & patching |
+| 5 | NgSpice compilation from source (with GHDL patches) |
+| 6 | Verilator setup & compilation |
+| 7 | Python environment & package installation |
+| 8 | GTK resource bundling (icons, themes, schemas) |
+| 9 | KiCad & OMEdit library bundling |
+| 10 | AppImage creation & packaging |
+
+---
+
+## 🖥️ Usage
+
+Once the build is complete, you will find `eSim-2.5.AppImage` (~625 MB) in the `build-eSim-AppImage/` directory.
+
+### Running the AppImage
+```bash
+./build-eSim-AppImage/eSim-2.5.AppImage
+```
+
+> [!TIP]
+> You can copy this single file to **any other Linux distribution** and it will run without needing to install eSim's complex dependency tree!
+
+### What's Included
+When you launch the AppImage, you get access to:
+- **eSim** — Main schematic/simulation GUI
+- **KiCad** — Schematic & PCB editor (launched from within eSim)
+- **OMEdit** — OpenModelica editor for Modelica models
+- **NgSpice** — Circuit simulation engine (runs automatically from eSim)
+- **NGHDL** — VHDL digital model integration
+- **NgVeri** — Verilog digital model integration via Verilator
+
+---
+
+## 🐧 Supported Distributions
+
+| Distribution | Package Manager | Status |
+|-------------|----------------|--------|
+| Ubuntu 20.04+ | `apt` | ✅ Fully tested |
+| Debian 11+ | `apt` | ✅ Fully tested |
+| Linux Mint 21+ | `apt` | ✅ Fully tested |
+| Fedora 38+ | `dnf` | ✅ Fully tested |
+| Arch Linux | `pacman` | ✅ Fully tested |
+| Manjaro | `pacman` | ✅ Fully tested |
+| openSUSE Leap/Tumbleweed | `zypper` | ✅ Supported |
+| RHEL / CentOS 8+ | `dnf` / `yum` | ✅ Supported |
+
+> [!NOTE]
+> The **build** can be performed on any supported distribution. The resulting AppImage is portable and can **run** on any x86_64 Linux distribution with FUSE support.
+
+---
+
+## 🔧 Troubleshooting
+
+### FUSE Error (Ubuntu 22.04+)
+If the AppImage fails to run with a message about FUSE:
+```bash
+sudo apt update && sudo apt install libfuse2
+```
+
+### OMEdit Not Opening
+If OMEdit fails to launch, it's usually a missing Qt5 library. The builder automatically handles this by:
+- Bundling Ubuntu `.deb` libraries for OpenSceneGraph, Qt5WebKit, ICU, and omniORB
+- Installing native Qt5 modules (`qt5-declarative`, `qt5-sensors`, `qt5-location`) during the build
+
+To manually check: run `ldd eSim.AppDir/usr/bin/OMEdit.bin | grep "not found"` inside the build directory.
+
+### Python Import Errors
+If you see `ModuleNotFoundError` for PyQt5 or other Python packages:
+- On **Arch**: Ensure `python-pyqt5` is installed (`sudo pacman -S python-pyqt5`)
+- On **Fedora**: Ensure `python3-PyQt5` is installed (`sudo dnf install python3-PyQt5`)
+
+### Build Failures
+Common causes:
+- **Interrupted internet** during large downloads (KiCad AppImage is ~600 MB)
+- **Missing disk space** (at least 5 GB required)
+- **Unsupported architecture** (only x86_64 is currently supported)
+
+---
+
+## 📁 Project Structure
+
+```
+eSim_Universal_packagemanager_linux/
+├── build-appimage.sh         # Main build script (~7800 lines)
+├── README.md                 # This file
+└── build-eSim-AppImage/      # Created during build
+    ├── downloads/            # Downloaded tools & dependencies
+    ├── eSim.AppDir/          # AppImage filesystem
+    │   ├── AppRun            # Entry point launcher
+    │   ├── usr/
+    │   │   ├── bin/          # eSim, KiCad, OMEdit, NgSpice binaries
+    │   │   ├── lib/          # Bundled shared libraries
+    │   │   └── share/        # eSim source, resources, models
+    │   └── ...
+    └── eSim-2.5.AppImage     # Final portable AppImage
+```
+
+---
+
+## 🏗️ Architecture & Design
+
+The build system uses a **layered approach** to handle cross-distribution compatibility:
+
+1. **Detection Layer** — Identifies the host distro and package manager
+2. **Dependency Layer** — Installs build-time and runtime dependencies using the native package manager
+3. **Compilation Layer** — Builds NgSpice from source with custom patches; compiles Verilator object files
+4. **Bundling Layer** — Copies all binaries, libraries, Python packages, GTK resources, and KiCad into the AppDir
+5. **Fallback Layer** — For libraries not available on the host system (e.g., OMEdit's Ubuntu-specific dependencies), downloads `.deb` packages from Ubuntu archives and extracts the needed `.so` files
+6. **Packaging Layer** — Creates the final AppImage using `appimagetool`
+
+---
+
+## 📜 License
+
+This project is part of the [FOSSEE](https://fossee.in/) initiative at IIT Bombay and follows the licensing of the bundled tools (primarily GPL v3). See the individual component headers for details.
+
+---
+
+*Developed for the eSim Community to provide a seamless simulation experience on Linux.*