CI/CD Introduction and Overview

Introduction to CI/CD

Consolidated from Introduction_to_CI_CD.md.

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CI/CD Overview and Diagram

Consolidated from CI_CD_Overview_and_Diagram.md with process summary, artifacts, deployment strategies, and cross-platform terminology table.

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Adopting CI/CD and Makefile Example

Consolidated from Adopting_CI_CD_and_Makefile.md with staged adoption advice and simple makefile.

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