Fix cron container so daily wiki export actually runs

The cron has been silently failing every day since 2026-03-28. Four
independent bugs were stacked:

1. cron/entrypoint.sh: env dump used `sed` to wrap each line in
   `export `, but values with spaces (e.g. GIT_SSH_COMMAND, OIDC_SCOPES)
   produced lines like `export GIT_SSH_COMMAND=ssh -o UserKnownHosts...`
   which `export` parses as a flag and aborts. busybox ash treats the
   builtin error as fatal, so `. /etc/environment.sh; script.sh` never
   reaches the script. Now single-quote each value with proper escaping.

2. cron/Dockerfile: NODE_PATH only works for CommonJS `require()`, not
   ESM `import`. The export script is `"type": "module"` and failed with
   "Cannot find package 'gray-matter'". Install deps at /app/node_modules
   instead — Node ESM walks up from /app/scripts and finds it there.

3. docker-compose.yml: `~/.ssh:/root/.ssh:ro` — DokPloy does NOT expand
   `~`, so it created a literal `~` directory inside the deployment dir
   and mounted that empty dir. The container had no SSH key. Use the
   absolute host path `/root/.ssh` instead.

4. cron/entrypoint.sh: even with the SSH key, `git push` would fail
   because the git remote is HTTPS and the host's git server runs on
   port 2222 (set in /root/.ssh/config). Add a `pushInsteadOf` rewrite
   so push uses SSH while DokPloy can keep fetching via HTTPS, and stop
   re-running ssh-keyscan against the wrong port — copy the host's
   known_hosts (which already has the :2222 entry) instead.

docker-compose.yml

@@ -80,7 +80,9 @@ services:
       - ./content:/app/content
       - ./.git:/app/.git
       - /var/run/docker.sock:/var/run/docker.sock:ro
-      - ~/.ssh:/root/.ssh:ro
+      # Absolute path required: DokPloy does NOT expand ~ and would otherwise
+      # create a literal "~" directory under the deployment dir.
+      - /root/.ssh:/root/.ssh:ro
       - ./backups:/backups/outline
     env_file:
       - .env