feat(gmw): route all LLM traffic through 9router

GMW moves off omniroute (100.121.180.82:20128) and off the direct NVIDIA
vision endpoint onto 9router, which runs on the same host as both services
(127.0.0.1:4014) — loopback avoids the TLS/proxy hop and localhost calls
bypass 9router's remote-key guard.

- gateway + backend: AI_LLM_BASE_URL default -> http://127.0.0.1:4014/v1
- drop stale 'omniroute' router references from comments/docs now that the
  active router is 9router (llmClient, llmCaller, ARCHITECTURE, AGENTS)

Verified against 9router before wiring: model 'text' -> gemini-3.5-flash-lite
(SSE, as the pipeline expects), 'multimodal' -> nemotron-3-nano-omni answers
image input, and gemini/gemini-embedding-001 returns 3072 dims — matching the
existing Qdrant collections (no reindex needed). The GMW key is already
registered in 9router's apiKeys table.

typecheck + lint + tests green (gateway 138, backend 37 excluding e2e).

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

@@ -92,7 +92,7 @@ export async function callModerationLLM(
             jsonResponse: { type: "json_object" },
             retries: 0,
             signal,
-            // Router (omniroute) always streams SSE even when the
+            // Router 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