ci: add security scanning and SBOM to release pipeline

- ci.yml: add security job (gitleaks, cargo-audit, cargo-deny, trivy fs)
- release.yml: restructure into build-binary + build-docker matrix + release
  - build binary once on self-hosted, reuse across all Docker builds
  - trivy image scan per matrix variant, results to GitHub Security tab
  - SBOM generation in SPDX and CycloneDX formats attached to release
- deny.toml: cargo-deny policy (allowed licenses, banned openssl, crates.io only)
- Dockerfile: remove Rust build stage, use pre-built binary
- Dockerfile.astra, Dockerfile.redos: FROM scratch for Russian certified OS support

deny.toml

@@ -0,0 +1,41 @@
+# cargo-deny configuration
+# https://embarkstudios.github.io/cargo-deny/
+
+[advisories]
+# Vulnerability database (RustSec)
+db-urls = ["https://github.com/rustsec/advisory-db"]
+ignore = []
+
+[licenses]
+# Allowed open-source licenses
+allow = [
+    "MIT",
+    "Apache-2.0",
+    "Apache-2.0 WITH LLVM-exception",
+    "BSD-2-Clause",
+    "BSD-3-Clause",
+    "ISC",
+    "Unicode-DFS-2016",
+    "Unicode-3.0",
+    "CC0-1.0",
+    "OpenSSL",
+    "Zlib",
+    "MPL-2.0",           # Mozilla Public License — ok for binary linking
+]
+copyleft = "warn"        # GPL etc — warn, don't block
+unlicensed = "deny"
+
+[bans]
+multiple-versions = "warn"
+deny = [
+    # Prefer rustls over openssl for static builds and supply chain cleanliness
+    { name = "openssl-sys" },
+    { name = "openssl" },
+]
+skip = []
+
+[sources]
+unknown-registry = "warn"
+unknown-git = "warn"
+# Allow only the official crates.io index
+allow-registry = ["https://github.com/rust-lang/crates.io-index"]