chore(readme): flip to single-source .adoc + derived .md (ADR-004 pilot)

boj-server is one of two estate repos with a genuine Markdown-only consumer
(Glama, which renders README.adoc as raw markup). Per ADR-004, flip it from a
hand-authored README.md to authored README.adoc + CI-derived README.md:

- README.adoc: new canonical source (bootstrapped from the prior README.md
  via the ADR-004 recipe; sets :idprefix:/:idseparator: - so the TOC anchors
  resolve on GitHub and re-derive cleanly).
- README.md: now a GENERATED artefact (banner stamped; do not hand-edit).
  Verified faithful: 11/11 TOC anchors resolve, 12/12 badges intact (incl.
  Glama), blockquote + inline code round-trip clean.
- ECOSYSTEM.a2ml: [publishing.readme] declaration (consumer=glama) — the
  machine-readable opt-in the derive workflow reads.
- .github/workflows/readme-derive.yml: caller for the standards reusable;
  regenerates + freshness-checks README.md on changes.

Local verification (pandoc 3.10 + asciidoctor 2.0.26): vocab gate 98.7%,
normalised freshness byte-identical, anchor guard satisfied.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/readme-derive.yml

@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: MPL-2.0
+# README single-source derivation (ADR-004): README.adoc is canonical;
+# README.md is derived for the Glama MCP directory (Markdown-only renderer).
+# This caller delegates to the standards reusable, which reads the
+# [publishing.readme] declaration in .machine_readable/*/ECOSYSTEM.a2ml,
+# regenerates README.md behind a vocabulary gate, and fails-and-tells if the
+# committed README.md is stale relative to README.adoc.
+name: README Derive
+
+on:
+  push:
+    branches: [main, master]
+    paths:
+      - README.adoc
+      - README.md
+      - .machine_readable/**/ECOSYSTEM.a2ml
+  pull_request:
+    paths:
+      - README.adoc
+      - README.md
+      - .machine_readable/**/ECOSYSTEM.a2ml
+
+permissions:
+  contents: read
+
+jobs:
+  readme-derive:
+    # Pinned to the standards commit that introduced readme-derive-reusable.yml.
+    # Repin to include hyperpolymath/standards#476 (anchor-ID convention guard)
+    # once it lands on main; this repo's README.adoc already satisfies it.
+    uses: hyperpolymath/standards/.github/workflows/readme-derive-reusable.yml@db12a6ad3ef9076d5f7bdcf98d7d15cf8547555a

.machine_readable/6a2/ECOSYSTEM.a2ml

@@ -48,3 +48,15 @@ seed-nodes = [
 ]
 dns-status = "hyperpolymath.dev undelegated — registrar action needed (see container/fly/DNS-SETUP.adoc); *.fly.dev hostnames operative"
 federation-protocol = "Umoja gossip (X25519 + ChaCha20-Poly1305, UDP 9999, IPv6)"
+
+# ── Publishing (ADR-004: README single-source derivation) ──────────────────
+# README.adoc is canonical; README.md is DERIVED (GENERATED banner) for Glama,
+# which renders Markdown only. Regenerated + freshness-checked by the
+# readme-derive workflow. Never hand-edit README.md.
+[publishing.readme]
+canonical = "README.adoc"
+derive    = true
+format    = "gfm"
+path      = "README.md"
+consumer  = "glama"
+reason    = "Glama MCP directory renders Markdown only; canonical README.adoc renders as raw markup there"