auth: fix problems with the ollama keypairs (#12373)

* auth: fix problems with the ollama keypairs

This change adds several fixes including:
  - reading in the pubkey files correctly
  - fixing the push unit test to create a keypair file in a temp directory
  - not return 500 errors for normal status error

cmd/cmd_test.go

@@ -525,6 +525,9 @@ func TestPushHandler(t *testing.T) {
 			defer mockServer.Close()
 
 			t.Setenv("OLLAMA_HOST", mockServer.URL)
+			tmpDir := t.TempDir()
+			t.Setenv("HOME", tmpDir)
+			t.Setenv("USERPROFILE", tmpDir)
 			initializeKeypair()
 
 			cmd := &cobra.Command{}