Add copilot instructions (#3390)

Author: ildyria

.github/copilot-instructions.md

@@ -0,0 +1,8 @@
+Any new php file should contain the license header and has a single blank line after the opening PHP tag.
+The variable name should be in snake_case.
+In Requests, if a user is provided by the query it is placed in the $this->user2.
+In Requests, $this->user is reserved for the user making the request.
+We do not use blade view, we use Vue3 instead.
+Use Typescript in composition API for Vue3. Use PrimeVue for UI components.
+Do not use await async calls in Vue3, use .then() instead.
+Do not use const function = () => {}, use function functionName() {} instead.