docs(project_rules): add signing requirement for commits

Add rule 5 to enforce commit signing for better traceability and security.

.trae/rules/project_rules.md

@@ -1,4 +1,5 @@
 1. All code and conversations must be in English regardless of the language sent!
 2. When I send a request I dont need a confirmation if i want to make the change, I just need the change to be done!
 3. Anytime major changes are done make a new commit, no extended explanations needed!
-4. Never Push to github, just git add and git commit!
+4. Never Push to github, just git add and git commit!
+5. When commiting always sign it!