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/llmClient.ts

@@ -94,7 +94,7 @@ type LLMResponseChunk = {
  * `delta.content`; falls back to reasoning fields so reasoning-only models
  * still produce usable aggregated text. Providers differ in the field name:
  * - DeepSeek-style / Cloudflare gemma → `delta.reasoning_content`
- * - mimo (via 9router) streams reasoning in `delta.reasoning` +
+ * - mimo (via omniroute) streams reasoning in `delta.reasoning` +
  *   `delta.reasoning_details[].text` (content:"") — without these fallbacks
  *   vision aggregation came back empty ("Vision API null response").
  * Exported for unit tests.
@@ -225,7 +225,7 @@ export function buildLlmParams(
       reasoning: { enabled: false },
       // vLLM / Qwen / litellm
       chat_template_kwargs: { enable_thinking: false },
-      // Anthropic / Claude-format (9router exposes thinkingFormat
+      // Anthropic / Claude-format (omniroute exposes thinkingFormat
       // "claude-adaptive" / "claude-budget" on its reasoning models)
       thinking: { type: "disabled" },
     } as Record<string, unknown>);