fix: Correct .gitignore to track cmd/server/main.go

The pattern 'server' was too broad and ignored the cmd/server/ directory.
Changed to '/server' to only ignore the binary at root level.
This fixes the missing main.go file in the repository.

.gitignore

@@ -5,9 +5,9 @@
 *.so
 *.dylib
 
-# Go build output
-server
-project-notes
+# Go build output (binaries only, not source directories)
+/server
+/project-notes
 cmd/server/server
 
 # Test binary, built with `go test -c`