fix: migrate deployment from Hetzner to Coolify (#1)

## Summary
- Add Coolify deployment configuration (docker-compose, healthchecks, network setup)
- Replace deploy-hetzner CI job with Coolify webhook deploy
- Externalize postgres, qdrant, S3 for Coolify environment
- Remove services not needed for SDK deployment (voice, jitsi, synapse)

## All changes since branch creation
- Coolify docker-compose with healthchecks for all services
- CI pipeline: deploy-hetzner → deploy-coolify (simple webhook curl)
- QDRANT_API_KEY support in rag-service
- Alpine-compatible Dockerfile fixes

Co-authored-by: Sharang Parnerkar <parnerkarsharang@gmail.com>
Reviewed-on: #1

backend-core/Dockerfile

@@ -43,11 +43,12 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && rm -rf /var/lib/apt/lists/*
 
 # Install DevSecOps tools (gitleaks, trivy, grype, syft)
-ARG TARGETARCH=arm64
+ARG TARGETARCH
 RUN set -eux; \
+    ARCH="${TARGETARCH:-$(dpkg --print-architecture)}"; \
     # Gitleaks
     GITLEAKS_VERSION=8.21.2; \
-    if [ "$TARGETARCH" = "arm64" ]; then GITLEAKS_ARCH=arm64; else GITLEAKS_ARCH=x64; fi; \
+    if [ "$ARCH" = "arm64" ]; then GITLEAKS_ARCH=arm64; else GITLEAKS_ARCH=x64; fi; \
     curl -sSfL "https://github.com/gitleaks/gitleaks/releases/download/v${GITLEAKS_VERSION}/gitleaks_${GITLEAKS_VERSION}_linux_${GITLEAKS_ARCH}.tar.gz" \
       | tar xz -C /usr/local/bin gitleaks; \
     # Trivy