improve: add clean coding standards copilot instructions

.github/copilot-instructions.md

@@ -0,0 +1,14 @@
+### Clean Coding standards
+
+Code, documentation and feedback shall be in line with principal level scientific elegance, minimalism, conciseness and precision.
+That means explicitly long, expressive, pronounceable well chosen names instead of short abbreviating names.
+For example appLICATION, depENDENCIES, repoSITORY, syncHRONIZATION, devELOPMENT, prodUCTION, tempORARY, authENTICATION, authORIZATION, deployMENT, credENTIALS.
+Trying to "save" letters is unprofessional and decreases readability.
+Blacklist typical lazy abbreviations, but whitelist very popular context-free acronyms such as OIDC, API, CPU, GPU.
+Code is more often read than written and most of the costs come from maintenance.
+Code and documentation must be readable as proper technical English text, especially traditional elaborated English.
+What is not tested is not supported.
+Automation is the best documentation.
+We do trunk-based development in the main branch.
+A contributor must not raise generated PRs that he has not reviewed first.
+The expectation for the contibutor is that he must understand all changes he is proposing as if he had written the changes himself.