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/gitea/client.ts

@@ -138,6 +138,17 @@ 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 ${key} is ignored: it comes from the vault`);
+}
+
 export class GiteaClient {
   readonly baseUrl: string;
   private readonly tokens: TokenSource;
@@ -151,7 +162,8 @@ export class GiteaClient {
   /**
    * Build from the module's resolved environment. The URL comes from MESH_GITEA_URL (the mesh's own
    * name), falling back to the bare GITEA_URL and to the forge's loopback port. The token, in order:
-   * one configured in settings or the environment (MESH_GITEA_TOKEN / GITEA_TOKEN), which wins; else
+   * one configured in the environment (MESH_GITEA_TOKEN / GITEA_TOKEN), which wins — never a setting, which is
+   * ignored and said (hq issue 342); else
    * one the module mints for itself with the admin account the vault delivered and keeps in its own
    * state (token.ts; hq issue 100). Throws only when neither is possible, naming what is missing,
    * rather than hand back a client that fails on first use.
@@ -159,7 +171,8 @@ export class GiteaClient {
   static fromEnv(env: NodeJS.ProcessEnv = process.env): GiteaClient {
     const cfg = meshConfig(env.MESH_GITEA_CONFIG_FILE);
     const url = cfg.url ?? env.MESH_GITEA_URL ?? env.GITEA_URL ?? `http://127.0.0.1:${env.GITEA_PORT ?? "3000"}`;
-    const configured = cfg.token ?? env.MESH_GITEA_TOKEN ?? env.GITEA_TOKEN;
+    ignoreSecretSetting(cfg, "token");
+    const configured = env.MESH_GITEA_TOKEN ?? env.GITEA_TOKEN;
     if (configured) return new GiteaClient(url, new ConfiguredToken(configured));
     return new GiteaClient(url, MintedToken.fromEnv(url, env));
   }