fix(scheduler,config): preserve ENV schedule; add AUTO_MIRROR_REPOS auto-mirroring

- Prevent Automation UI from overriding schedule:
      - mapDbScheduleToUi now parses intervals robustly (cron/duration/seconds) via parseInterval
      - mapUiScheduleToDb merges with existing config and stores interval as seconds (no lossy cron conversion)
      - /api/config passes existing scheduleConfig to preserve ENV-sourced values
      - schedule-sync endpoint uses parseInterval for nextRun calculation
  - Add AUTO_MIRROR_REPOS support and scheduled auto-mirror phase:
      - scheduleConfig schema includes autoImport and autoMirror
      - env-config-loader reads AUTO_MIRROR_REPOS and carries through to DB
      - scheduler auto-mirrors imported/pending/failed repos when autoMirror is enabled before regular sync
      - docker-compose and ENV docs updated with AUTO_MIRROR_REPOS
  - Tests pass and build succeeds

src/pages/api/config/index.ts

@@ -87,7 +87,10 @@ export const POST: APIRoute = async ({ request }) => {
     }
 
     // Map schedule and cleanup configs to database schema
-    const processedScheduleConfig = mapUiScheduleToDb(scheduleConfig);
+    const processedScheduleConfig = mapUiScheduleToDb(
+      scheduleConfig,
+      existingConfig ? existingConfig.scheduleConfig : undefined
+    );
     const processedCleanupConfig = mapUiCleanupToDb(cleanupConfig);
 
     if (existingConfig) {

src/pages/api/job/schedule-sync-repo.ts

@@ -8,6 +8,7 @@ import type {
   ScheduleSyncRepoResponse,
 } from "@/types/sync";
 import { createSecureErrorResponse } from "@/lib/utils";
+import { parseInterval } from "@/lib/utils/duration-parser";
 
 export const POST: APIRoute = async ({ request }) => {
   try {
@@ -72,8 +73,17 @@ export const POST: APIRoute = async ({ request }) => {
 
     // Calculate nextRun and update lastRun and nextRun in the config
     const currentTime = new Date();
-    const interval = config.scheduleConfig?.interval ?? 3600;
-    const nextRun = new Date(currentTime.getTime() + interval * 1000);
+    let intervalMs = 3600 * 1000;
+    try {
+      intervalMs = parseInterval(
+        typeof config.scheduleConfig?.interval === 'number'
+          ? config.scheduleConfig.interval
+          : (config.scheduleConfig?.interval as unknown as string) || '3600'
+      );
+    } catch {
+      intervalMs = 3600 * 1000;
+    }
+    const nextRun = new Date(currentTime.getTime() + intervalMs);
 
     // Update the full giteaConfig object
     await db