Pass manifest env to background systemd-run updates

pikit-api.py

@@ -750,16 +750,13 @@ def start_background_task(mode: str):
     assert mode in ("apply", "rollback"), "invalid mode"
     unit = f"pikit-update-{mode}"
     flag = f"--{mode}-update"
-    cmd = [
-        "systemd-run",
-        "--unit",
-        unit,
-        "--quiet",
-        "/usr/bin/env",
-        "python3",
-        str(API_PATH),
-        flag,
-    ]
+    cmd = ["systemd-run", "--unit", unit, "--quiet"]
+    # Pass manifest URL/token if set in environment
+    if DEFAULT_MANIFEST_URL:
+        cmd += [f"--setenv=PIKIT_MANIFEST_URL={DEFAULT_MANIFEST_URL}"]
+    if AUTH_TOKEN:
+        cmd += [f"--setenv=PIKIT_AUTH_TOKEN={AUTH_TOKEN}"]
+    cmd += ["/usr/bin/env", "python3", str(API_PATH), flag]
     subprocess.run(cmd, check=False)