Fix 2 failing CI tests

- describeSpawnFailure("vllm"): the test expects an actionable install
  command in the message (matching the existing installCommand() helper
  already used by explainStartupFailure); reused it for all three backends
  instead of hand-written prose that had drifted out of sync with the test.
- recommendModels VRAM test: aggregateUsableVramGB is intentionally rounded
  to 1 decimal place (same precision as every other GB figure this function
  reports), so 21.12 * 2 GPUs displays as 42.2, not the unrounded 42.24 the
  test asserted.

Author: voidstackloop

app/src/local-server-manager.ts

@@ -60,9 +60,9 @@ export function installCommand(backend: LocalBackendId): string {
 }
 
 export function describeSpawnFailure(backend: LocalBackendId): string {
-    if (backend === "mlx") return "Couldn't launch MLX. Install mlx-lm on an Apple Silicon Mac and verify the configured Python interpreter.";
-    if (backend === "vllm") return "Couldn't launch vLLM. Install vLLM in Linux/WSL and verify that its CUDA or ROCm requirements match the GPU driver.";
-    return "Couldn't launch ROCm llama-server. Configure a working ROCm/HIP llama-server executable and verify ROCm device access.";
+    if (backend === "mlx") return `Couldn't launch MLX. Install mlx-lm on an Apple Silicon Mac (${installCommand("mlx")}) and verify the configured Python interpreter.`;
+    if (backend === "vllm") return `Couldn't launch vLLM. Install it in Linux/WSL (${installCommand("vllm")}) and verify that its CUDA or ROCm requirements match the GPU driver.`;
+    return `Couldn't launch ROCm llama-server. ${installCommand("rocm")} and verify ROCm device access.`;
 }
 
 async function commandSucceeds(command: string, args: string[]): Promise<boolean> {

app/src/system-specs.test.ts

@@ -67,7 +67,10 @@ describe("recommendModels", () => {
         });
         const result = recommendModels(specs);
         // 48GB aggregate remains visible, but is not treated as one pool.
-        expect(result.usableVRAMGB).toBeCloseTo(42.24);
+        // aggregateUsableVramGB is rounded to 1 decimal place (same precision
+        // as every other GB figure this function reports), so the raw
+        // 21.12 * 2 = 42.24 product displays as 42.2, not 42.24.
+        expect(result.usableVRAMGB).toBeCloseTo(42.2, 1);
     });
 
     it("does not treat aggregate VRAM as one GPU", () => {