feat: rewrite voice-assistant in Go

Replace Python voice assistant with Go for smaller container images.
Uses handler-base Go module for NATS, health, telemetry, and all service clients.

- Full pipeline: STT → embed → Milvus → rerank → LLM → TTS
- Base64 audio encode/decode
- Dockerfile: multi-stage golang:1.25-alpine → scratch
- CI: Gitea Actions with lint/test/release/docker/notify

Dockerfile

@@ -1,9 +1,23 @@
-# Voice Assistant - Using handler-base with audio support
-ARG BASE_TAG=latest
-FROM ghcr.io/billy-davies-2/handler-base:${BASE_TAG}
+# Build stage
+FROM golang:1.25-alpine AS builder
 
 WORKDIR /app
 
-COPY voice_assistant.py .
+RUN apk add --no-cache ca-certificates
 
-CMD ["python", "voice_assistant.py"]
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-w -s" -o /voice-assistant .
+
+# Runtime stage
+FROM scratch
+
+COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY --from=builder /voice-assistant /voice-assistant
+
+USER 65534:65534
+
+ENTRYPOINT ["/voice-assistant"]