Initial commit: AirCoding V1.0.0 Alpha architecture baseline

Complete architecture document set with multi-model review remediation:
- Frozen interface contracts, runtime semantics, DB schemas
- Event/tool/error/provider registries
- Scheduler and main agent state machines
- C4 module/code views, solution architecture, baseline V1
- Multi-model review reports and joint assessment
- Phase-gate remediation complete (P0/P1/P2/UX resolved)
- Implementation plan with T-000A through T-045
- Reference folders kept as placeholders only

reference/openai-codex/.devcontainer/Dockerfile

@@ -0,0 +1,27 @@
+FROM ubuntu:24.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+# enable 'universe' because musl-tools & clang live there
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    software-properties-common && \
+    add-apt-repository --yes universe
+
+# now install build deps
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    build-essential curl git ca-certificates \
+    pkg-config libcap-dev clang musl-tools libssl-dev just && \
+    rm -rf /var/lib/apt/lists/*
+
+# Ubuntu 24.04 ships with user 'ubuntu' already created with UID 1000.
+USER ubuntu
+
+# install Rust + musl target as dev user
+RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal && \
+    ~/.cargo/bin/rustup target add aarch64-unknown-linux-musl && \
+    ~/.cargo/bin/rustup component add clippy rustfmt
+
+ENV PATH="/home/ubuntu/.cargo/bin:${PATH}"
+
+WORKDIR /workspace