fix(security) : replace real secrets in .env with placeholders and create .env.example

Secrets moved to .env.local (gitignored). Added .env.example for new developers.
Also added .idea/ and docker/.env.docker.local to .gitignore and removed them from tracking.

Tickets: T-001, T-013, T-018

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -22,3 +22,11 @@
 ###> lexik/jwt-authentication-bundle ###
 /config/jwt/*.pem
 ###< lexik/jwt-authentication-bundle ###
+
+###> ide ###
+.idea/
+###< ide ###
+
+###> docker local ###
+docker/.env.docker.local
+###< docker local ###