Add .github/copilot-instructions.md

[Copilot]

Establishes Copilot coding agent instructions so automated contributions stay consistent with repo conventions.

What's included

• Component structure — canonical directory layout with all required files (CMakeLists.txt, idf_component.yml, headers, source, example), including notes on optional partitions.csv and multiple sdkconfig.defaults.* variants
• Documentation checklist — how to update doc/Doxyfile (both INPUT and EXAMPLE_PATH), and what RST + example MD files to create under doc/en/ (or the appropriate subdirectory)
• CI checklist — how to add entries in alphabetical order to build.yml (matrix target) and upload_components.yml (component path)
• Existing component updates — reminder to keep README, idf_component.yml, RST docs, and CI files in sync when modifying a component
• Code style & build — C++20, .clang-format, espp namespace conventions, ESP-IDF v5.5.1 toolchain

Original prompt

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This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

Any time a change is made, please ensure the relevant component documentation, examples, configuration files are also up to date. Finally, if a new component is added, please ensure the documentation configuration files and the continuous integration / build and component publishing files are updated. Below is a list describing where such files are and how they are structured. If a new component is added, make sure to follow the structure of the other components in the repo (example directory structure provided below)

example component directory structure:

components/task
├── CMakeLists.txt
├── README.md
├── example
│   ├── CMakeLists.txt
│   ├── README.md
│   ├── main
│   │   ├── CMakeLists.txt
│   │   └── task_example.cpp
│   └── sdkconfig.defaults
├── idf_component.yml
├── include
│   ├── run_on_core.hpp
│   ├── task.hpp
│   └── task_formatters.hpp
└── src
└── task.cpp

Note that some component examples have multiple sdkconfig.defaults files if they support multiple specific hardware configurations and some examples may have partitions.csv as well.

Below is a snippet of the top-level doc folder with the Doxyfile for configuring paths to component includes and component examples, as well as the doc/en directory containing RST files for short form docs and md files which simply point to the actual component example readme files.

doc
├── Dockerfile
├── Doxyfile
├── README.md
├── conf_common.py
├── doxygen-known-warnings.txt
├── en
│   ├── adc
│   ├── base_component.rst
│   ├── base_peripheral.rst
│   ├── battery
│   ├── binary_log_example.md
│   ├── bldc
│   ├── ble
│   ├── button.rst
│   ├── button_example.md
│   ├── byte90.rst
│   ├── byte90_example.md
...

Each component should have:

1. include files properly referenced in Doxyfile (keep in alphabetical order)
2. example cpp file properly referenced in Doxyfile (keep in alphabetical order)
3. Minimum of 1 RST file in doc/en (or relevant subdirectory) for the component
4. md file in doc/en (or relevant subdirectory) which points to the example's README

Finally, we have a few important CI files that need to be maintained / updated for any new component:

.github/workflows
├── build.yml
└── upload_components.yml

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ✨ Set up Copilot instructions #603

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[github-actions]

✅Static analysis result - no issues found! ✅

[Copilot]

Pull request overview

This PR establishes GitHub Copilot coding agent instructions to ensure automated contributions stay consistent with the ESPP repository's conventions and structure.

Changes:

• Adds comprehensive .github/copilot-instructions.md documenting component structure, documentation requirements, CI configuration, code style, and maintenance guidelines for the ~120 components in this ESP32/ESP-IDF C++ library