docs: rewrite README into comprehensive English documentation by Tomáš Bělák

[RemindCZ]

Motivation

• Replace the original Czech README with a comprehensive, production-grade English technical document authored in the name of Tomáš Bělák to improve usability and onboarding for MT5 + CUDA workflows.
• Consolidate API details, lifecycle, async training, telemetry, state persistence, MT5 integration, build/deploy, and troubleshooting into a single structured README for easier reference.
• Preserve the requested small personal thank-you note to Anička at the end of the document.

Description

• Replace the entire readme.md with a reorganized document that includes Executive Summary, Architecture and Design Goals, API Model and Lifecycle Contract, Training Engine Modes, Progress Telemetry, State Persistence, Full MT5 Integration Workflow, Build and Deployment, Performance Recommendations, Troubleshooting Matrix, repository map, and license.
• Add an author line (Tomáš Bělák), badges, clarified API examples and signatures (e.g. DN_Create, DN_TrainAsync, DN_GetProgressAll, DN_PredictBatch) and explicit tensor/data contracts.
• Append the requested closing personal note in Czech thanking Anička for help with late-night thinking about overly complicated code.

Testing

• Verified the new readme.md content and structure using file-inspection commands sed -n '1,220p' readme.md, sed -n '220,500p' readme.md, and nl -ba readme.md to confirm sections and final note.
• Confirmed repository file listing with rg --files and checked working-tree status with git status --short, and these checks completed successfully.
• Prepared PR metadata through the repo tooling and validated that the updated readme.md is staged in the working tree and present in the branch.

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Codex Task