v1.3.3

fix: resolve model release deadlock & single-job atomic pipeline

Root cause: GitHub Release 'model-xasr-zh-en-480ms-r1' existed as
empty shell (assets:[]) causing immutability check to exit 1 before
upload could ever run — a permanent deadlock.

Changes:
- model-release.yml: merge validate+publish into single job (no more
  550MB cross-job artifact transfer); immutability check now only
  blocks when the actual asset file is already attached
- acquire-base-model.sh: add deterministic local packaging fallback
  when GitHub Release returns 404, ensuring CI never fails on missing
  remote asset
- base-model.lock.json: update SHA256 to match current deterministic
  archive (changed because base-model.json now embeds per-file hashes)
- all platform workflows: clean up legacy echolet-model-* cache globs

Verified: 2x deterministic builds produce identical SHA256, all 11
tests pass, download-official-assets.sh cache-hit path works.