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/.github/actions/setup-msvc-env/action.yml

@@ -0,0 +1,17 @@
+name: setup-msvc-env
+description: Expose an MSVC developer environment for the requested Windows target.
+inputs:
+  target:
+    description: Rust target triple that will be built on this Windows runner.
+    required: true
+  host-arch:
+    description: Optional Visual Studio host architecture override.
+    required: false
+    default: ""
+
+runs:
+  using: composite
+  steps:
+    - name: Expose MSVC SDK environment
+      shell: pwsh
+      run: '& "$env:GITHUB_ACTION_PATH/setup-msvc-env.ps1" -Target "${{ inputs.target }}" -HostArch "${{ inputs.host-arch }}"'