feat(pipeline): analysis-based firmware SBOM from tramiton

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>

compliance-agent/Cargo.toml

@@ -15,6 +15,9 @@ compliance-dast = { path = "../compliance-dast" }
 # available to the onboarding classifier. NOTE: CI must be able to fetch this
 # private repo (see the git-auth step in .gitea/workflows/ci.yml).
 tramiton-core = { git = "ssh://git@gitea.meghsakha.com:22222/sharang/tramiton.git", tag = "v0.4.0" }
+# tramiton-repro's `libraries_from_inputs` turns a build plan's fetched inputs
+# into the SBOM-friendly library list (analysis-based firmware SBOM, no build).
+tramiton-repro = { git = "ssh://git@gitea.meghsakha.com:22222/sharang/tramiton.git", tag = "v0.4.0" }
 serde = { workspace = true }
 serde_json = { workspace = true }
 tokio = { workspace = true }