[andersalm]

Part of #89

Removes model preparation from the release. Models were dropped from the release (#236) and the catalogue pin is signed by a lost test key, so models will come back later as their own signed publication.

• Deletes model-package-handoff.py and its test, docs/MODEL_PACKAGE_HANDOFF.md, fetch/fetch-model.sh, fetch-model-smoke.py, release-upstream-assets-test.py (model-only) and the root model-catalog.json.
• Drops model_catalog from components.json. With no pin, setup installs no catalogue and Home's Models and Marketplace views report unconfigured and list no models, with no error.
• Removes model CAR retention: ELASTOS_RELEASE_MODEL_* in prepare/publish scripts, finalize-models in release-platform-input.py, the signer's catalogue signing mode and MODEL_COMPONENTS, model packaging in release-upstream-assets.py, model_retention admission in release_publication.rs and the CAR import in elastos publish-release.
• Keeps verification of a pinned catalogue (setup, installed release, signer, publish checks) for the future publication, and takes the Rust part of #217 follow-ups: bound catalogue fetch, retire URL model docs #233: the Carrier catalogue read is bounded to 128 KiB and refused from the declared size, with its regression test.
• Removes the source-home and local-carrier steps that copied the deleted catalogue, and the product-data checks of it.

Net lines: +94 / -5,654 (-5,560), 27 files.

Local checks: publish-platform-artifacts-test.py OK; release-platform-input-test.py, prepare-release-platform-test.py and release-signer-test.py fail only on the same cases as develop when run on this Mac under /tmp (path permission and pinned interpreter checks); node --test check-product-data.test.mjs 84/84; cargo test -p elastos-server --bin elastos -- publish:: 38/38; cargo test -p elastos-server --lib -- setup:: installed_release:: capsule_inventory:: release_publication:: carrier:: 417 passed, 1 failure that also fails on develop locally (media-tools ffmpeg parent permissions).