feat(docs): version-bound release documentation served at /docs

Adds a docs pipeline so each release has a version-bound Markdown
document (docs/releases/vX.Y.Z.md) rendered publicly in the app:

- sync-release-docs.mjs copies docs/releases/*.md into the toolrate
  public dir and generates index.json before every dev/build
- /docs lists all releases; /docs/:version renders the sanitized
  Markdown (marked + DOMPurify, typography styles)
- template + workflow documented in docs/README.md
- current release (v0.6.0) documented as the first entry

scripts/src/sync-release-docs.mjs

@@ -0,0 +1,87 @@
+// Copies docs/releases/*.md into the toolrate frontend's static public dir
+// and generates index.json (version list) so the app can render /docs.
+//
+// Run before `vite build` (Vite copies public/ -> dist/public verbatim), and
+// before `vite dev` so the docs are available locally too.
+//
+// Usage: node scripts/src/sync-release-docs.mjs
+
+import { readdir, readFile, copyFile, mkdir, rm, writeFile } from "node:fs/promises";
+import { resolve, join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const root = resolve(fileURLToPath(new URL("../..", import.meta.url)));
+const sourceDir = resolve(root, "docs/releases");
+const targetDir = resolve(root, "artifacts/toolrate/public/docs");
+
+const isReleaseFile = (name) => /^v\d+\.\d+\.\d+\.md$/.test(name);
+
+function parseVersion(name) {
+  return name.replace(/\.md$/, "");
+}
+
+// Semantic-ish comparison: v0.6.0 > v0.5.0 > v0.4.2
+function cmp(a, b) {
+  const pa = parseVersion(a).slice(1).split(".").map(Number);
+  const pb = parseVersion(b).slice(1).split(".").map(Number);
+  for (let i = 0; i < 3; i++) {
+    if ((pa[i] ?? 0) !== (pb[i] ?? 0)) return (pa[i] ?? 0) - (pb[i] ?? 0);
+  }
+  return 0;
+}
+
+function extractTitle(content) {
+  const m = content.match(/^#\s+(.+)$/m);
+  return m ? m[1].trim() : null;
+}
+
+function extractDate(content) {
+  // e.g. "**Datum:** 2026-08-03" or "**Date:** 2026-08-03" in the header block.
+  // Match the first ISO date that follows a Datum/Date label, tolerating
+  // bold markers/colons around it.
+  const m = content.match(/(?:Datum|Date)[^\d\n]{0,20}(\d{4}-\d{2}-\d{2})/);
+  return m ? m[1] : null;
+}
+
+async function main() {
+  let names;
+  try {
+    names = (await readdir(sourceDir)).filter(isReleaseFile);
+  } catch (err) {
+    if (err.code === "ENOENT") {
+      console.warn(`[sync-release-docs] ${sourceDir} not found; nothing to sync`);
+      return;
+    }
+    throw err;
+  }
+
+  if (names.length === 0) {
+    console.warn("[sync-release-docs] no release docs found; clearing target dir");
+  }
+
+  names.sort(cmp).reverse();
+
+  await rm(targetDir, { recursive: true, force: true });
+  await mkdir(targetDir, { recursive: true });
+
+  const index = [];
+  for (const name of names) {
+    const content = await readFile(join(sourceDir, name), "utf8");
+    await copyFile(join(sourceDir, name), join(targetDir, name));
+    index.push({
+      version: parseVersion(name),
+      file: name,
+      title: extractTitle(content) ?? parseVersion(name),
+      date: extractDate(content) ?? null,
+    });
+  }
+
+  await writeFile(join(targetDir, "index.json"), JSON.stringify(index, null, 2));
+
+  console.log(`[sync-release-docs] synced ${names.length} release doc(s) -> ${targetDir}`);
+}
+
+main().catch((err) => {
+  console.error("[sync-release-docs] failed:", err);
+  process.exit(1);
+});