chore: remove old Live ATC system (engine, editor, decision trees)

BREAKING: Removes communicationsEngine (1,429 LOC), LLM decision
router (1,137 LOC), decision tree MongoDB models, editor UI/API,
pm.vue page, and all related types/services. Simplifies PTT endpoint
to STT-only. Moves getOpenAIClient to normalize.ts.

Prepares for v2 Phase Machine reimplementation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/utils/openaiDecision.ts

@@ -1,10 +0,0 @@
-// utils/openaiDecision.ts
-import type { LLMDecisionInput, LLMDecisionResult } from '../types/llm'
-
-/** Client-seitig: ruft den Backend-Endpunkt auf */
-export async function decideNextStateLLM(input: LLMDecisionInput): Promise<LLMDecisionResult> {
-    return await $fetch<LLMDecisionResult>('/api/llm/decide', {
-        method: 'POST',
-        body: input
-    })
-}