Centralize server config handling

This moves all the env var reading into one central module
and logs the loaded config once at startup which should
help in troubleshooting user server logs

server/envconfig/config_test.go

@@ -0,0 +1,20 @@
+package envconfig
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestConfig(t *testing.T) {
+	os.Setenv("OLLAMA_DEBUG", "")
+	LoadConfig()
+	require.False(t, Debug)
+	os.Setenv("OLLAMA_DEBUG", "false")
+	LoadConfig()
+	require.False(t, Debug)
+	os.Setenv("OLLAMA_DEBUG", "1")
+	LoadConfig()
+	require.True(t, Debug)
+}