Fix dangling config binds: seed configs to a stable host path

Root cause of the Grafana "readdirent /etc/grafana/dashboards: no such file or
directory": the CI runner checks out into an ephemeral act workspace that is
removed after the job, so binding the compose config files straight from it
dangles the mounts in the long-lived containers (verified the act source dir is
emptied after the job). caddy/otelcol/prometheus/tempo read their config once at
startup so they survive, but would break on a restart — same latent bug.

Fix (mirrors ../galaxy-game's $HOME/.galaxy-dev/monitoring): the deploy job seeds
the config dirs to a stable $HOME/.scrabble-deploy and the compose binds them via
${SCRABBLE_CONFIG_DIR:-.} (local runs keep "."). Documented in the compose header,
deploy/README.md and the ci.yaml step.

.gitea/workflows/ci.yaml

@@ -188,6 +188,16 @@ jobs:
           DICT_VERSION: ${{ vars.TEST_DICT_VERSION }}
           LOG_LEVEL: ${{ vars.TEST_LOG_LEVEL }}
         run: |
+          # Seed the config files to a stable host path. The runner checks out into
+          # an ephemeral act workspace that is removed after the job, which would
+          # dangle the compose config bind mounts in the long-lived containers
+          # (e.g. Grafana then logs "no such file or directory"). Bind from a stable
+          # dir instead (mirrors ../galaxy-game's $HOME/.galaxy-dev/monitoring).
+          conf="$HOME/.scrabble-deploy"
+          rm -rf "$conf"
+          mkdir -p "$conf"
+          cp -r caddy otelcol prometheus tempo grafana "$conf"/
+          export SCRABBLE_CONFIG_DIR="$conf"
           docker compose --ansi never build --progress plain
           docker compose --ansi never up -d --remove-orphans