Global code ovehaul - remove CAS and other, add 15 minute greet check

- Remove CAS, as it no longer works for us
- Remove other checks
- Implement 15 minute greet timeout check
- Fix chat logos
- Ditch thirdparty logger, use stdlib log facility wrapper for logging

.golangci.yml

@@ -2,7 +2,7 @@ version: "2"
 run:
   go: "1.24"
   modules-download-mode: readonly
-  tests: false
+  tests: true
   allow-parallel-runners: true
 linters:
   default: none