Publish immutable short firmware download links

Mirror pinned GitHub release bytes at shorter version-specific Pages URLs. Verify size, SHA-256 and firmware format before publishing, and preserve deployed alias identities across later site builds.

Add RAK4631 Full Companion 1.17.1.10 preview2 UF2 and native DFU ZIP aliases, a short-download directory, documentation and CI regressions. Existing flashing tools use the ZIP URL without losing board-family checks.

Validation: 16 short-link and Pages guard regressions, hosted-doc routing tests, firmware picker tests, full MkDocs build and exact UF2/ZIP byte checks.

scripts/docs_firmware_shortlinks.py

@@ -0,0 +1,50 @@
+"""Publish version-pinned firmware downloads at short, real binary URLs."""
+
+import html
+import logging
+import os
+from pathlib import Path
+import sys
+
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+from firmware_shortlinks import download_url, load_manifest, mirror, validate_immutable
+
+
+MARKER = "<!-- firmware-shortlinks:table -->"
+
+
+def registry(config):
+    return load_manifest(Path(config["docs_dir"]) / "_data/firmware_shortlinks.json")
+
+
+def on_page_markdown(markdown, page, config, **kwargs):
+    if MARKER not in markdown:
+        return markdown
+    data = registry(config)
+    base = config["site_url"].rstrip("/") + "/d/"
+    rows = ["<table><thead><tr><th>Firmware</th><th>Short download link</th>"
+            "<th>Original release</th></tr></thead><tbody>"]
+    for link in data["links"]:
+        label = html.escape(link["label"], quote=True)
+        alias = base + link["filename"]
+        original = download_url(data, link).split("/releases/download/", 1)[0]
+        original += "/releases/tag/" + link["releaseTag"]
+        rows.append(
+            "<tr><td>" + label + "</td><td><a href=\"" + html.escape(alias, quote=True)
+            + "\">" + html.escape(link["filename"]) + "</a></td><td><a href=\""
+            + html.escape(original, quote=True) + "\">Release</a></td></tr>")
+    rows.append("</tbody></table>")
+    return markdown.replace(MARKER, "\n".join(rows))
+
+
+def on_post_build(config, **kwargs):
+    data = registry(config)
+    previous = os.environ.get("MESHCORE_SHORTLINKS_PREVIOUS")
+    if previous:
+        validate_immutable(load_manifest(Path(previous)), data)
+    cache = Path(os.environ.get(
+        "MESHCORE_SHORTLINKS_CACHE",
+        str(Path(config.config_file_path).resolve().parent / ".cache/firmware-shortlinks")))
+    outputs = mirror(data, Path(config["site_dir"]) / "d", cache)
+    logging.getLogger("mkdocs.plugins.firmware_shortlinks").info(
+        "Published %d checksum-verified short firmware downloads", len(outputs))