fix: harden Pi lifecycle recovery

backend/src/config.ts

@@ -196,6 +196,7 @@ export function loadConfig(env: Record<string, string | undefined>): AppConfig {
     maxImportBytes: positiveImportLimit(env.THT_WORKSPACE_MAX_IMPORT_BYTES, 10 * 1024 * 1024),
     maxImportEntries: positiveImportLimit(env.THT_WORKSPACE_MAX_IMPORT_ENTRIES, 32),
   };
+  const settingsFile = env.SETTINGS_FILE ?? "data/settings.json";
   return {
     host: env.HOST ?? "127.0.0.1",
     port: Number(env.PORT ?? 8787),
@@ -206,8 +207,8 @@ export function loadConfig(env: Record<string, string | undefined>): AppConfig {
     sessionStorage,
     defaults: { provider: env.PI_PROVIDER, model: env.PI_MODEL, thinking: env.PI_THINKING },
     maxPiProcesses: Number(env.MAX_PI_PROCESSES ?? 4),
-    settingsFile: env.SETTINGS_FILE ?? "data/settings.json",
-    maintenanceFile: env.THT_MAINTENANCE_FILE ?? "data/maintenance.json",
+    settingsFile,
+    maintenanceFile: env.THT_MAINTENANCE_FILE ?? path.join(path.dirname(settingsFile), "maintenance.json"),
     dataRoot: env.THT_DATA_ROOT,
     ollamaEnsureTimeoutMs: Number(env.OLLAMA_ENSURE_TIMEOUT_MS ?? 60000),
     secretsFile,