release(v1.7.40-alpha): fix tarball root perms at source so OTA can't 500 again

v1.7.38 and v1.7.39 both shipped with `./` inside the frontend tarball marked
drwx------ (700). Tar extraction preserves archive perms, so every node that
pulled the OTA landed with /opt/archipelago/web-ui at 700, nginx (www-data)
returned 500 "permission denied" on every page, and the browser showed
"Internal Server Error nginx". .116 hit this on both v1.7.38 and v1.7.39
rollouts. The v1.7.39 runtime self-heal in main.rs was the wrong layer —
systemd's ReadOnlyPaths namespace made /opt/archipelago read-only from inside
the archipelago service, so chmod from there returned EROFS.

Root cause: create-release-manifest.sh used mktemp -d (700 default umask) for
staging, then tar preserved that 700 in the archive's root entry.

Fix the archive itself:
- chmod 755 staging dir + `find -type d -exec chmod 755` + `-type f chmod 644`
  before tar, so the on-disk entries are correct.
- tar --owner=0 --group=0 --mode='u=rwX,go=rX' to normalize archive perms
  belt-and-braces in case file-mode drift ever reappears.
- Post-tar verify: `tar tvzf | head -1` must show drwxr-xr-x at root, or
  the release script aborts before the manifest is even generated.

Binary unchanged semantically — the main.rs self-heal stays in as a last-
resort belt (can't hurt on nodes whose FS isn't namespace-isolated), and the
update.rs in-extractor chmod stays in so v1.7.40-onwards extractors are
double-safe. The authoritative fix is the archive.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

neode-ui/src/views/settings/AccountInfoSection.vue

@@ -180,6 +180,16 @@ init()
               </button>
             </div>
             <div class="overflow-y-auto flex-1 min-h-0 space-y-6 pr-1">
+              <!-- v1.7.40-alpha -->
+              <div>
+                <div class="flex items-center gap-2 mb-3">
+                  <span class="text-xs font-mono px-2 py-0.5 rounded bg-orange-500/20 text-orange-300">v1.7.40-alpha</span>
+                  <span class="text-xs text-white/40">Apr 22, 2026</span>
+                </div>
+                <div class="space-y-3 text-sm text-white/80 pl-3 border-l border-white/10">
+                  <p>Proper fix for the 500 / Internal Server Error after update. The v1.7.38 and v1.7.39 frontend archives had the wrong permissions baked into the archive itself — the tarball's root directory entry was private, so every node that extracted it ended up with a web UI directory nginx couldn't read. v1.7.40 packages the archive with correct world-readable permissions from the start, so no node ever sees the 500 again.</p>
+                </div>
+              </div>
               <!-- v1.7.39-alpha -->
               <div>
                 <div class="flex items-center gap-2 mb-3">