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>

apps/web/app/api/internal/cron/weekly-digest/route.ts

@@ -18,7 +18,7 @@ import {
 import { sendEmail, weeklyDigestHtml } from "@/lib/email";
 
 // Internal cron endpoint — triggered by the `digest-cron` container on a weekly
-// schedule (see docker/compose.prod.yml). Not part of the public API surface;
+// schedule (see compose.prod.yml). Not part of the public API surface;
 // protected by a shared secret rather than user auth.
 //
 // Computes, for every user: new followers / new comments / new ratings on