[Doc] End to End Workflow and Architecture

A markdown report on end to end architecture, workflow and expectation with mermaid diagrams. Dont use LLM for anything else than structure and grammar.

It should also include the rationale behind decisions, for eg. why we decided to go with clients clipboard but couldn't for now, separate client server setting, trackpad region for mirror and all. Also, consider discussions from successful issues and PRs to get the decision points.

In short, this should be enough to explain the entire vision and work to anyone without looking at the codebase.