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

llm/memory.go

@@ -3,12 +3,11 @@ package llm
 import (
 	"fmt"
 	"log/slog"
-	"os"
-	"strconv"
 
 	"github.com/ollama/ollama/api"
 	"github.com/ollama/ollama/format"
 	"github.com/ollama/ollama/gpu"
+	"github.com/ollama/ollama/server/envconfig"
 )
 
 // This algorithm looks for a complete fit to determine if we need to unload other models
@@ -50,15 +49,8 @@ func EstimateGPULayers(gpus []gpu.GpuInfo, ggml *GGML, projectors []string, opts
 	for _, info := range gpus {
 		memoryAvailable += info.FreeMemory
 	}
-	userLimit := os.Getenv("OLLAMA_MAX_VRAM")
-	if userLimit != "" {
-		avail, err := strconv.ParseUint(userLimit, 10, 64)
-		if err != nil {
-			slog.Error("invalid setting, ignoring", "OLLAMA_MAX_VRAM", userLimit, "error", err)
-		} else {
-			slog.Info("user override memory limit", "OLLAMA_MAX_VRAM", avail, "actual", memoryAvailable)
-			memoryAvailable = avail
-		}
+	if envconfig.MaxVRAM > 0 {
+		memoryAvailable = envconfig.MaxVRAM
 	}
 
 	slog.Debug("evaluating", "library", gpus[0].Library, "gpu_count", len(gpus), "available", format.HumanBytes2(memoryAvailable))