refactor(compose): rename docker network archive-net to archiv-net

The docker network was the only `archive-*` identifier in either
compose file; everything else (user, db, bucket, service account,
project name) uses the `archiv-*` spelling. Reviewers' eyes stuttered
on it on the prod compose review (round 2 of PR #499 — Markus and
Tobi). Renamed in both prod and dev compose for consistency and
updated the single doc reference to the dev-project-prefixed
network name.

Operational note: applying this change to a running stack will
recreate the network on the next `docker compose up`; containers
restart, named volumes are unaffected.

`docker compose config --quiet` passes for both compose files and
for the staging profile. Sweep confirms zero `archive-net`
references remain in the tree.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/infrastructure/ci-gitea.md

@@ -166,7 +166,7 @@ jobs:
           timeout 30 bash -c \
             'until docker compose -f docker-compose.yml -f docker-compose.ci.yml exec -T db pg_isready -U archive_user; do sleep 2; done'
       - name: Connect job container to compose network
-        run: docker network connect familienarchiv_archive-net $(cat /etc/hostname)
+        run: docker network connect familienarchiv_archiv-net $(cat /etc/hostname)
       - uses: actions/setup-java@v4
         with:
           java-version: '21'