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/atuin-18.16.1/.github/workflows/codespell.yml

@@ -0,0 +1,28 @@
+# Codespell configuration is within .codespellrc
+---
+name: Codespell
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  codespell:
+    name: Check for spelling errors
+    runs-on: depot-ubuntu-24.04
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+      - name: Codespell
+        uses: codespell-project/actions-codespell@v2
+        with:
+          # This is regenerated from commit history
+          # we cannot rewrite commit history, and I'd rather not correct it
+          # every time
+          exclude_file: CHANGELOG.md