Keep every password, token and API key the vault's, never a setting (hq issue 342)

A setting outranked the vault: baserow, grafana, letta and unifi merged a layer's
password over the ${secret:...} in their runtime config, and the gitea,
home-assistant, icecast, influxdb, mailu and nextcloud clients read the settings
file before the vault's file. A secret in a setting cannot be rotated and is read
back by the settings verb.

The four files now keep their password protected, so the controller refuses a
setting of it. The six clients ignore a secret in the settings file and say so
once, by key and never with the value; icecast reads its admin password from the
vault's file. checks/secrets refuses a mergeable file whose secret a layer could
replace; searxng's nested server.secret_key is listed as known until the
controller protects a nested key.

modules/nextcloud/client.ts

@@ -32,6 +32,17 @@ function meshConfig(file?: string): Record<string, string> {
   catch { return {}; }
 }
 
+/**
+ * A password, token or API key is the vault's, never a setting (novox/hq issue 342): a value for one of
+ * them in the settings file is ignored, and that is said once — by its key, never with its value.
+ */
+const saidIgnored = new Set<string>();
+function ignoreSecretSetting(cfg: Record<string, unknown>, key: string): void {
+  if (cfg[key] === undefined || saidIgnored.has(key)) return;
+  saidIgnored.add(key);
+  console.error(`the setting ${key} is ignored: it comes from the vault`);
+}
+
 export class NextcloudClient {
   constructor(
     private readonly container: string,
@@ -53,7 +64,8 @@ export class NextcloudClient {
     const ocsUrl = cfg.url ?? env.MESH_NEXTCLOUD_URL ?? `http://127.0.0.1:${env.NEXTCLOUD_PORT ?? "80"}`;
     const adminUser = cfg.user ?? env.MESH_NEXTCLOUD_ADMIN_USER ?? "admin";
     const passwordFile = env.MESH_NEXTCLOUD_ADMIN_PASSWORD_FILE;
-    const adminPassword = cfg.password ?? env.MESH_NEXTCLOUD_ADMIN_PASSWORD
+    ignoreSecretSetting(cfg, "password");
+    const adminPassword = env.MESH_NEXTCLOUD_ADMIN_PASSWORD
       ?? (passwordFile ? readFileSync(passwordFile, "utf8").trim() : undefined);
     if (!adminPassword) {
       throw new Error("no Nextcloud admin password — set MESH_NEXTCLOUD_ADMIN_PASSWORD_FILE " +