Fix ONNX CPU Spiking, Padding Infinite Loops & UI Guide

[Casezy]

This PR introduces massive stability, optimization, and feature additions for offline translation, AI translation, and UI improvements over several version iterations (v1.3 - v1.5).

?? Version 1.5 Updates: ONNX & CPU Optimizations

1. ONNX Language Setup Guide: Added a built-in UI guide to help users install new language models.
2. ONNX CPU Spiking Resolved: Forced IntraOpNumThreads=1 and InterOpNumThreads=1 to run ONNX on a single thread, greatly reducing CPU usage.
3. Infinite Loop & Garbage Text Fix: Suppressed the pad token (54795) to prevent infinite decode loops in Greedy Search.
4. Language Switch Detection: Properly dispose ONNX model sessions when switching language pairs.
5. Resilient Model Downloads: Improved the model downloader by using .tmp files and atomic renaming to prevent corrupted models.

?? Version 1.4 Updates: New Translation Engines

1. NVIDIA NIM Integration: Added support for NVIDIA NIM (NVIDIA Inference Microservices) as a translation engine.
2. NVIDIA Riva Support: Integrated NVIDIA Riva for advanced AI-driven workflows.
3. ONNX Offline Translation (Opus-MT): Integrated completely offline translation capabilities using ONNX CPU execution for HuggingFace opus-mt models, including an on-the-fly JSON patcher for Rust tokenizer incompatibilities.
4. Configuration Save Crash: Fixed a major bug that caused the application to Force Close when exiting due to an unimplemented GetHashCode() in GamepadHotKeyInfo.cs.

?? Version 1.3 Updates: AI & UI Improvements

1. AI Translator Integration: Added support for translating via Advanced AI Models (Gemini, OpenRouter, DeepSeek, ChatGPT/OpenAI compatible APIs).
2. Local LibreTranslate Support: Fully integrated a completely offline, local LibreTranslate server support with an automatic lifecycle manager.
3. Clear Chat Hotkey (ALT+C): A newly implemented global hotkey to instantly clear the chat bubble/translation screen.
4. Proxy Error Fixes: Resolved persistent proxy errors that blocked connections to translators.
5. UI & Stability: Restored Anti Double-Click on the "Run LibreTranslate" button and removed the highly unstable experimental Dark Theme.