Refactor reverse proxy to support API base path and update example configuration. Changed base URLs in config.example.yaml to use HTTPS and the new /api/ prefix. Enhanced reverse proxy logic in reverse.go to build upstream paths correctly and added a new test for path rewriting with the API base path in reverse_test.go.

config.example.yaml

@@ -29,15 +29,15 @@ servers:
     path_prefix: /v1
     # authorization_env: TELEMT_API_AUTH
 
-  # ivx: порт 9091 как у типичного Telemt API; при необходимости — https и другой порт.
+  # ivx: API за префиксом /api/ на HTTPS.
   - alias: gt1
-    base_url: http://gt1.ivx.su:9091
+    base_url: https://gt1.ivx.su/api/
     path_prefix: /v1
 
   - alias: gt2
-    base_url: http://gt2.ivx.su:9091
+    base_url: https://gt2.ivx.su/api/
     path_prefix: /v1
 
   - alias: gt3
-    base_url: http://gt3.ivx.su:9091
+    base_url: https://gt3.ivx.su/api/
     path_prefix: /v1