refactor(docker): run all containers as root, add compact log format support

- Docker: remove appuser creation and USER directive in all 7 Dockerfiles
- observability: recognize APP_LOG_FORMAT=compact as non-JSON pretty output

docker/app.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 openssh-client procps git \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/app /bin
-USER appuser
 EXPOSE 3000
 CMD ["app"]

docker/email.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/email-worker /bin
-USER appuser
 EXPOSE 8084
 CMD ["email-worker"]

docker/gingress.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/gingress /bin
-USER appuser
 EXPOSE 80 443 8080
 ENTRYPOINT ["gingress"]

docker/githook.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 git \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/git-hook /bin
-USER appuser
 EXPOSE 8083
 CMD ["git-hook"]

docker/gitserver.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 git openssh-client \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/gitserver /bin
-USER appuser
 EXPOSE 8021 2222
 CMD ["gitserver"]

docker/metrics.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/metrics-aggregator /bin
-USER appuser
 EXPOSE 9090
 CMD ["metrics-aggregator"]

docker/static.Dockerfile

@@ -2,9 +2,7 @@ FROM ubuntu:24.04
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates libssl3 \
     && rm -rf /var/lib/apt/lists/*
-RUN useradd --system --create-home appuser
-WORKDIR /home/appuser
+WORKDIR /app
 COPY ./target/release/static-server /bin
-USER appuser
 EXPOSE 8081
 CMD ["static-server"]

libs/observability/src/tracing_fmt.rs

@@ -41,7 +41,7 @@ pub fn instance_id() -> String {
 fn use_json() -> bool {
     match std::env::var("APP_LOG_FORMAT").as_deref() {
         Ok("json") => true,
-        Ok("pretty") => false,
+        Ok("pretty") | Ok("compact") => false,
         _ => !std::io::stdout().is_terminal(), // TTY → pretty, non-TTY → json
     }
 }