docs(readme): convert README.adoc -> Markdown README.md (#32)

README must be real Markdown to render in GitHub community-health, the GitHub
profile, and external MCP directories (Glama) — AsciiDoc shows as raw markup
there. pandoc asciidoc->GFM, badges fixed to clickable, SPDX header kept as an
HTML comment, duplicate README.adoc removed.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath

README.adoc

@@ -0,0 +1,72 @@
+<!--
+SPDX-License-Identifier: CC-BY-SA-4.0
+SPDX-FileCopyrightText: 2025-2026 Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
+-->
+
+Consolidated monorepo holding Flatracoon’s operating-system and
+networking-stack components, plus the supporting CI / RSR scaffolding.
+
+# Components
+
+- `os/` — operating-system core. The bare-metal / userspace layer of the
+  Flatracoon OS proper.
+
+- `netstack/` — independent network stack implementation (sits above or
+  alongside `os/`).
+
+Each component is autonomous in its build, but they share licensing, CI,
+and the estate-wide governance bundle inherited from
+`hyperpolymath/standards`.
+
+# Why a monorepo
+
+This repo was consolidated from previously-separate clones into a single
+monorepo to share CI / governance / dependency-version state across the
+two components. Each subdirectory still has its own `Justfile` /
+`Cargo.toml` / build entry points; the monorepo just collapses the
+operational overhead.
+
+# Quickstart
+
+```bash
+git clone git@github.com:hyperpolymath/flatracoon.git
+cd flatracoon
+
+# OS:
+cd os/
+just build && just test
+
+# Netstack:
+cd ../netstack/
+just build && just test
+```
+
+# Architecture
+
+See <a href="TOPOLOGY.md" class="md">TOPOLOGY</a> for the visual
+architecture map and the component-by-component completion dashboard.
+
+# Status
+
+- **Licence**: MPL-2.0. See [LICENSE](LICENSE); `LICENSES/` carries the
+  full REUSE-compliant set.
+
+- **Estate role**: research / experimental — not yet a downstream
+  consumer of stable services.
+
+- **Audit findings**: see `docs/tech-debt-2026-05-26.md` if present
+  (added by the 2026-05-26 estate tech-debt scan).
+
+# Contributing
+
+See <a href="CONTRIBUTING.md" class="md">CONTRIBUTING</a>. All commits
+must be GPG-signed and follow conventional-commit conventions
+(estate-wide policy from `hyperpolymath/standards`).
+
+# Companion repositories
+
+- [`hyperpolymath/standards`](https://github.com/hyperpolymath/standards)
+  — canonical estate-wide standards.
+
+- [`hyperpolymath/rsr-template-repo`](https://github.com/hyperpolymath/rsr-template-repo)
+  — the RSR scaffold this repo follows.