chore: move docker/ compose files and infra to repo root

Moved compose.yml, compose.prod.yml, DEPLOY.md, traefik/, and cron/ out
of docker/ into the repo root (docker/ removed). Updated every reference:

- Dockerfile: COPY paths for the cron stage
- .dockerignore: dropped the now-unneeded docker/!docker-cron
  exclude+exception pair (cron/ is just a normal top-level dir now, no
  special-casing needed)
- compose.prod.yml: build context ".." -> "." (Dockerfile and compose
  files are now siblings, not one level apart)
- CLAUDE.md, DEPLOY.md, compose.yml, traefik/epicure.yml,
  cron/run-digest.sh, weekly-digest route.ts: path references in comments/
  docs

Verified: both compose files validate, and all three Dockerfile targets
(runner/cron/migrator) build clean via a local --no-cache docker build
from the new layout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.dockerignore

@@ -5,6 +5,4 @@
 .git
 .env*
 !.env.example
-docker
-!docker/cron
 *.md