Step 23 sessions B+C: tools/remote wraps, verified live on mih34

The wrapper's config writing is gone: --env-file FILE selects the
target instance (default .env; named like docker's flag — --env means a
single variable there), the init fragment named by WERKATOR_INIT_CONFIG
is uploaded and installed remotely via 'werkator init --apply', and
instance-start places the .htaccess that init now generates. The
heredoc/sed machine-config writing is deleted; control-token delegates
to the werkator CLI; check-prerequisites uploads werkdock and runs its
doctor — tools/werkator-build-prerequisites.sh retires. The idle-check
and port-forward port lookups read the effective config via
config:print, so a port living in the applied fragment is found too.

Verified live against mih34 with the .env.mih34 + .env.mih34.yml pair
(gitignored via the new /.env.* rule): update, doctor PASS 6/6,
repo-init applying the fragment as the new layer, instance-start
placing the generated proxy and restarting the unit, control-token.

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

.gitignore

@@ -35,4 +35,5 @@ replay_pid*
 # Other
 /.local/
 /.env
+/.env.*