Three fixes the first real build exposed.

The import check caught what a lazy-import survey had missed: app.py
mounts every router, and a few touch libraries at module level rather
than lazily — soundfile (voice_convert), cv2/PIL (faceswap), litellm
(parser), websockets (broker client). A static walk of the import graph
from codai.api.app found the full set; they are now in core.txt with a
note saying why. torch and transformers are NOT among them, so they stay
per-profile.

torch moved into core so it becomes ONE shared layer. Nine images each
building their own copy would duplicate ~5 GB nine times — on disk and on
every push. Core is now its own RUN, identical across profiles, so all
nine share it.

A BuildKit pip cache mount means building all nine downloads torch once
rather than nine times, which matters when the link is also pulling
models.

build_all_capability_images.sh drives the set. Sequential on purpose:
they share the cache and the core layer, so parallel builds would race on
both. Each image must answer /healthz before the next starts.

Validated: coderai-embeddings built, imported and answered /healthz
(7259 MB) before this restructuring.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182DhR1eFNPQyGmDrpHbedY