fix(ci): integration finds its own Postgres when another repo's job shares the runner (#5104)

#5104 "CI integration lane connects to another repo's Postgres when two
integration jobs share the runner". Run 8358 took task 31950's Postgres
(another repo's integration job) with `--filter name=integration | head -n1`
and every test failed to connect. Read this job's GITEA-ACTIONS-TASK-<n>-
prefix from its own container and require exactly one Postgres under it.
(Docker ORs repeated name= filters, so the old one is dropped, not kept.)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.forgejo/workflows/ci.yml

@@ -80,14 +80,24 @@ jobs:
         # act_runner (swarm-runner) puts service containers on the default bridge
         # with no embedded DNS, so the hostname `postgres` won't resolve — we
         # discover the service container's bridge IP via the docker socket. The
-        # job name `integration` (no underscore) is the docker-ps name filter.
+        # job container and its Postgres share a task-number name prefix.
         run: |
           set -euxo pipefail
           echo "=== container landscape (diagnostic for filter scoping) ==="
           docker ps -a --format '{{.ID}} {{.Image}} -> {{.Names}}'
           echo "=== end landscape ==="
-          PG=$(docker ps --filter "name=integration" --filter "ancestor=postgres:16-alpine" -q | head -n1)
-          test -n "$PG"
+          # The runner's daemon is shared: another repo's integration job can be
+          # running beside this one, and `name=integration` matches its Postgres
+          # too (run 8358 took the wrong one and every test failed to connect).
+          # Scope to this job's own task: act_runner names every container of a
+          # task GITEA-ACTIONS-TASK-<n>-…, so read <n> from our own container
+          # (its id is in the /etc/hostname bind mount) and require one match.
+          SELF=$(grep -o '/containers/[0-9a-f]\{64\}/' /proc/self/mountinfo | head -n1 | cut -d/ -f3 || true)
+          SELF=${SELF:-$(hostname)}
+          TASK=$(docker inspect -f '{{.Name}}' "$SELF" | grep -o 'GITEA-ACTIONS-TASK-[0-9]*-')
+          test -n "$TASK"
+          PG=$(docker ps --filter "name=$TASK" --filter "ancestor=postgres:16-alpine" -q)
+          test "$(printf '%s\n' "$PG" | grep -c .)" -eq 1
           PG_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$PG")
           test -n "$PG_IP"
           export STEWARD_DATABASE_URL="postgresql+asyncpg://steward:steward@$PG_IP:5432/steward"