refactor: replace custom geo manager with Xray-core native geodata auto-update

Remove the panel-side custom geo download feature (service, controller,
/panel/api/custom-geo/* endpoints, CustomGeoResource model, UI tab) in
favor of Xray-core's native geodata section
(https://xtls.github.io/config/geodata.html).

- pass the top-level "geodata" key through xray.Config so it survives
  the template round-trip into the generated config
- add a Geodata Auto-Update section to the Xray Updates modal that
  edits geodata (cron schedule, download outbound, asset list) in the
  config template and restarts Xray on save
- previously downloaded geo files in the bin folder keep working in
  ext: routing rules; the orphaned custom_geo_resources table is left
  in place so existing source URLs stay recoverable

frontend/src/generated/examples.ts

@@ -250,17 +250,6 @@ export const EXAMPLES: Record<string, unknown> = {
     "up": 1048576,
     "uuid": "e18c9a96-71bf-48d4-933f-8b9a46d4290c"
   },
-  "CustomGeoResource": {
-    "alias": "",
-    "createdAt": 0,
-    "id": 0,
-    "lastModified": "",
-    "lastUpdatedAt": 0,
-    "localPath": "",
-    "type": "",
-    "updatedAt": 0,
-    "url": ""
-  },
   "FallbackParentInfo": {
     "masterId": 0,
     "path": ""