docs: clarify end-to-end execution pipeline

[Ymenjour]

Documentation-only clarification of the public FROG execution pipeline. Adds a root README section, expands the reference pipeline page, and adds companion notes for Example 05, FIR, and widget package hosting.

[Ymenjour]

Added a compact ASCII execution-pipeline diagram as ExecutionPipelineDiagram.md on this branch. The original box-drawing version was not inserted directly into Readme.md because the large README replacement was rejected by the tool; this standalone Markdown page keeps the diagram reviewable and can later be linked or folded into the README if desired.

[Ymenjour]

Updated Implementations/Reference/pipeline.md to include the execution-corridor diagram directly in the How the Current Reference Corridor Runs section. I used a GitHub/tool-compatible ASCII box diagram instead of Unicode box-drawing characters so the patch could be applied reliably.