feat(standards): add versioning + changelog standard, release templates, and Drone version guard

Add lib page 11 (SemVer contract, pre-1.0 rule, tag==version invariant, Keep a Changelog), the releasing wiki runbook, and canonical release templates (CHANGELOG.md, VERSION). Vendor them into the MCP bundle as templates/release + release.json and expose registry://release with list/get tools. Add a changelog component to the app template. Enforce the tag<->version contract in both Drone shapes: Type A check-version and the backfill loop verify pyproject version; Type B adds a VERSION guard step.

build.py

@@ -239,6 +239,8 @@ _TEMPLATE_COMPONENTS: list[dict[str, str]] = [
      "description": "OpenAPI contract skeleton."},
     {"kind": "pyproject", "path": "pyproject.toml", "placeholder": "",
      "description": "Packaging + dependency pins."},
+    {"kind": "changelog", "path": "CHANGELOG.md", "placeholder": "",
+     "description": "Keep a Changelog file with an [Unreleased] section (versioning standard)."},
     {"kind": "dockerfile", "path": "Dockerfile", "placeholder": "",
      "description": "API + worker image with private-index wiring."},
     {"kind": "dockerignore", "path": ".dockerignore", "placeholder": "",
@@ -412,6 +414,82 @@ def build_drone_templates(folder: Path, dry_run: bool = False) -> None:
           f"({len(manifest['components'])} components)")
 
 
+# ── Release standard bundle ───────────────────────────────────────────────────
+
+# The release artefacts shipped in ``src/templates/release``. One canonical
+# changelog (Keep a Changelog + SemVer) and the service version file. See
+# standards "11_versioning_and_changelog".
+_RELEASE_COMPONENTS: list[dict[str, str]] = [
+    {"kind": "changelog", "path": "CHANGELOG.md", "placeholder": "",
+     "description": "Keep a Changelog skeleton: one [Unreleased] section + compare links."},
+    {"kind": "version-file", "path": "VERSION", "placeholder": "",
+     "description": "Single-line SemVer source of truth for services and sites."},
+]
+
+
+def build_release_manifest(template_root: Path) -> dict[str, object]:
+    """Describe every artefact in the vendored release standard.
+
+    Args:
+        template_root (Path): The vendored ``templates/release`` directory.
+
+    Returns:
+        dict[str, object]: Manifest with the component entries and the
+        tag == version invariant.
+    """
+    components: list[dict[str, str]] = []
+    for entry in _RELEASE_COMPONENTS:
+        rel = entry["path"]
+        if not (template_root / rel).exists():
+            raise SystemExit(f"[ERR]  release template missing: {rel}")
+        components.append({
+            "kind": entry["kind"],
+            "path": rel,
+            "placeholder": entry["placeholder"],
+            "description": entry["description"],
+        })
+    return {
+        "project": "standards",
+        "template": "templates/release",
+        "invariant": "git tag == version file (enforced by the Drone guard)",
+        "components": components,
+    }
+
+
+def build_release_templates(folder: Path, dry_run: bool = False) -> None:
+    """Vendor ``folder/src/templates/release`` into ``<name>/mcp/templates/release``.
+
+    Ships the canonical ``CHANGELOG.md`` and ``VERSION`` in the MCP bundle so an
+    agent can drop them into a repo, and emits ``release.json`` describing them.
+
+    Args:
+        folder (Path): The hub folder owning ``src/templates/release``.
+        dry_run (bool): Print the plan without executing.
+    """
+    name = folder.name
+    src = folder / "src" / "templates" / "release"
+    if not src.is_dir():
+        return
+    out_dir = folder / "mcp" / "templates" / "release"
+    if dry_run:
+        print(f"[REL]  {name}  {src.relative_to(ROOT)}/** -> {out_dir.relative_to(ROOT)}/**")
+        return
+
+    if out_dir.exists():
+        shutil.rmtree(out_dir)
+    out_dir.parent.mkdir(parents=True, exist_ok=True)
+    shutil.copytree(
+        src, out_dir,
+        ignore=shutil.ignore_patterns("__pycache__", "*.pyc", ".git"),
+    )
+    manifest = build_release_manifest(out_dir)
+    (folder / "mcp" / "release.json").write_text(
+        json.dumps(manifest, indent=2, ensure_ascii=False), encoding="utf-8"
+    )
+    print(f"[REL]  {name}  release templates vendored to {out_dir.relative_to(ROOT)}/ "
+          f"({len(manifest['components'])} components)")
+
+
 # ── CLI ──────────────────────────────────────────────────────────────────────
 
 
@@ -432,6 +510,7 @@ def main() -> None:
         build_bundle(folder, dry_run=args.dry_run)
         build_templates(folder, dry_run=args.dry_run)
         build_drone_templates(folder, dry_run=args.dry_run)
+        build_release_templates(folder, dry_run=args.dry_run)
         build_html(folder, dry_run=args.dry_run)