Setup wizard: Test connection + Save & configure

Two-step device setup so the admin verifies before committing — and never touches
the device's own web UI.

- POST /api/setup/test (admin-only): healthCheck + checkPreconditions, no save and
  no device change. Returns device health + precondition issues.
- assign (Save) now also runs fixPreconditions (e.g. disables input_link_relay so
  a button press doesn't auto-fire its relay) before configuring the input push.
  Closes a gap where an assigned device could still auto-open. Fails the save with
  no DB row if device configuration fails (no orphan/half-configured rows).
- SetupWizard: wires config fields -> Test connection (health badge + precondition
  warnings) -> Save & configure; editing config resets prior test/save status.

Verified in-browser against the real device: Test -> ● ready + preconditions OK;
Save -> row persisted AND the device's Input Link URL written (push path matches
the saved device id). wiki/first-run-setup updated.

apps/web/src/api.ts

@@ -118,13 +118,32 @@ export async function discoverDevices(driverId: string): Promise<DiscoveredDevic
   return body.devices;
 }
 
+export type DeviceConfig = Record<string, string | number | boolean>;
+
+export interface TestResult {
+  health: { status: string; detail?: string };
+  preconditions: {
+    ok: boolean;
+    issues: { key: string; message: string; fixable: boolean }[];
+  };
+}
+
+/** Test a device config (reachability + preconditions) without saving. */
+export function testDevice(driverId: string, config: DeviceConfig): Promise<TestResult> {
+  return apiFetch<TestResult>("/api/setup/test", {
+    method: "POST",
+    body: JSON.stringify({ driverId, config }),
+  });
+}
+
 export interface AssignBody {
   lane: number;
   category: DeviceCategory;
   driverId: string;
-  config: Record<string, string | number | boolean>;
+  config: DeviceConfig;
 }
 
-export function assignDevice(body: AssignBody): Promise<unknown> {
+/** Save + configure the device (preconditions, push setup), then persist. */
+export function assignDevice(body: AssignBody): Promise<{ id: string }> {
   return apiFetch("/api/setup/assign", { method: "POST", body: JSON.stringify(body) });
 }