feat: strip down to audiobook-only, remove TTS/voice pages

Remove Home, VoiceManagement pages and all related components
(TTS forms, voice clone, history sidebar, onboarding), contexts
(App, History, Job), and hooks. Route / now redirects to /audiobook.
Also drop README, GitHub Actions workflows, screenshots, and add dev.sh.

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

dev.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+trap 'kill 0' EXIT
+
+(cd qwen3-tts-backend && conda run -n qwen3-tts uvicorn main:app --host 0.0.0.0 --port 8000 --reload 2>&1 | sed 's/^/[backend] /') &
+(cd qwen3-tts-frontend && npm run dev 2>&1 | sed 's/^/[frontend] /') &
+
+wait