Rename project from asr-v2 to speech

The project now covers both ASR and TTS, so "asr-v2" no longer fits.
Renames: quadlet (asr-v2.container -> speech.container, container
name, image tag), build.sh, FastAPI/UI title, and the OIDC env var
prefix (ASR_V2_* -> SPEECH_*, matching the renamed Authentik
provider/application slug "speech"). Internal Python packages
(asr/, tts/, core/) were already named generically and don't change.

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

quadlet/speech.container

@@ -1,11 +1,11 @@
 [Unit]
-Description=ASR v2 (faster-whisper + Qwen3-ASR)
+Description=Speech (ASR + TTS)
 After=network-online.target
 Wants=network-online.target
 
 [Container]
-ContainerName=asr-v2
-Image=localhost/asr-v2:latest
+ContainerName=speech
+Image=localhost/speech:latest
 Network=proxy
 User=983:983
 PublishPort=172.30.1.41:18101:8000