ci: add Astra Linux and RedOS parallel builds

Add Dockerfile.astra (astralinux/alse) and Dockerfile.redos (redos/redos)
for FSTEC-certified Russian OS targets. Update release.yml with a matrix
strategy that produces three image variants per release:
  - ghcr.io/.../nora:0.x.x          (Alpine, default)
  - ghcr.io/.../nora:0.x.x-astra    (Astra Linux SE)
  - ghcr.io/.../nora:0.x.x-redos    (RED OS)

Build stage is shared (musl static binary) across all variants.

Dockerfile.astra

@@ -0,0 +1,65 @@
+# syntax=docker/dockerfile:1.4
+
+# Build stage — static binary via musl (runs on any Linux)
+FROM rust:1.83-alpine AS builder
+
+RUN apk add --no-cache musl-dev curl
+
+WORKDIR /app
+
+# Copy manifests
+COPY Cargo.toml Cargo.lock ./
+COPY nora-registry/Cargo.toml nora-registry/
+COPY nora-storage/Cargo.toml nora-storage/
+COPY nora-cli/Cargo.toml nora-cli/
+
+# Create dummy sources for dependency caching
+RUN mkdir -p nora-registry/src nora-storage/src nora-cli/src && \
+    echo "fn main() {}" > nora-registry/src/main.rs && \
+    echo "fn main() {}" > nora-storage/src/main.rs && \
+    echo "fn main() {}" > nora-cli/src/main.rs
+
+# Build dependencies only (with cache)
+RUN --mount=type=cache,target=/usr/local/cargo/registry \
+    --mount=type=cache,target=/usr/local/cargo/git \
+    --mount=type=cache,target=/app/target \
+    cargo build --release --package nora-registry && \
+    rm -rf nora-registry/src nora-storage/src nora-cli/src
+
+# Copy real sources
+COPY nora-registry/src nora-registry/src
+COPY nora-storage/src nora-storage/src
+COPY nora-cli/src nora-cli/src
+
+# Build release binary (with cache)
+RUN --mount=type=cache,target=/usr/local/cargo/registry \
+    --mount=type=cache,target=/usr/local/cargo/git \
+    --mount=type=cache,target=/app/target \
+    touch nora-registry/src/main.rs && \
+    cargo build --release --package nora-registry && \
+    cp /app/target/release/nora /usr/local/bin/nora
+
+# Runtime stage — Astra Linux Special Edition (certified FSTEC OS)
+FROM astralinux/alse:latest
+
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends ca-certificates && \
+    rm -rf /var/lib/apt/lists/*
+
+RUN mkdir -p /data
+
+COPY --from=builder /usr/local/bin/nora /usr/local/bin/nora
+
+ENV RUST_LOG=info
+ENV NORA_HOST=0.0.0.0
+ENV NORA_PORT=4000
+ENV NORA_STORAGE_MODE=local
+ENV NORA_STORAGE_PATH=/data/storage
+ENV NORA_AUTH_TOKEN_STORAGE=/data/tokens
+
+EXPOSE 4000
+
+VOLUME ["/data"]
+
+ENTRYPOINT ["/usr/local/bin/nora"]
+CMD ["serve"]