Firmware/embedded targets got no SBOM: syft finds no package manifest in a
C/CMake/west source tree, and the real firmware bill-of-materials lives in the
build, not a lockfile. Derive it from tramiton's build-plan analysis instead.
New `pipeline::firmware_sbom`: runs `tramiton_core::provider::analyze` over the
already-ingested source (reusing the classification pass — no second clone) and
maps the plan's resolved libraries (`libraries_from_inputs`) + cross-toolchain
into `SbomEntry` records keyed by the target id. No binary upload, no nix build
toolchain in the agent image. Empty when tramiton can't form a build plan.
Wired into `classify_and_store` for firmware target types; the entries land in
`sbom_entries` so they show on the SBOM page and feed CVE matching like any
other SBOM. A full reproducible-build SBOM (sealed tramiton.lock with
artifact-level hashes) is the planned opt-in second phase.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>