chore: migrate AI LLM router from 9router to omniroute

Switch GMW's AI LLM base URL from 9router (https://9router.asepharyana.my.id/v1)
to omniroute on imrnes (http://100.121.180.82:20128/api/v1).

- Update default AI_LLM_BASE_URL in discord-gateway + backend config schemas
- Update .env.example documentation
- Update all 9router references in comments/docs/tests to omniroute
- Production BWS secret gmw_ai_llm_base_url already updated

Omniroute uses /api/v1 prefix (not /v1 like 9router), so the base URL
now correctly points at the right API path for the OpenAI SDK.

services/discord-gateway/src/modules/ai-moderation/llmCaller.ts

@@ -85,7 +85,7 @@ export async function callModerationLLM(
             jsonResponse: { type: "json_object" },
             retries: 0,
             signal,
-            // Router (9router / formerly omniroute) always streams SSE even when the
+            // Router (omniroute) always streams SSE even when the
             // request omits `stream`. In non-stream mode the OpenAI SDK waits
             // for the FULL body before parsing, so slow/long upstream streams
             // hit the 30s/60s timeout and abort mid-generation. Streaming mode