feat: migrate auth0mock from Node.js to Go

Refactor the application to a Go-based architecture for improved
performance and maintainability. Replace the Dockerfile to utilize a
multi-stage build process, enhancing image efficiency. Implement
comprehensive session store tests to ensure reliability and create
new OAuth handlers for managing authentication efficiently. Update 
documentation to reflect these structural changes.

.gitignore

@@ -1,3 +1,13 @@
-node_modules/
+# IDE
 .idea/
+.vscode/
+
+# Claude
 .claude/
+
+# Go
+auth0mock
+*.exe
+*.test
+*.out
+coverage.txt