fix: nextjs primary group + auto-create asset folders on entity create

THREE INTERLOCKING FIXES so editors stop hitting permission walls.

1) DOCKERFILE — gid 65533 (nogroup) on uploaded files
The container was creating files as 1001:65533 because Alpine's
`adduser --system --uid 1001 nextjs` doesn't set a primary group.
Files written through /api/assets ended up with `nogroup` ownership,
which surprised host sysadmins and made `chown -R 1001:1001` revert
on each fresh container start.

Fix: `adduser --system --uid 1001 --ingroup nodejs nextjs`. Now
every file written by the container is 1001:1001 (nextjs:nodejs),
matching the host conventions and the existing chown automation.

2) ENTRYPOINT — recursively normalise existing files
The recursive chown in scripts/docker-entrypoint.sh now sweeps every
subfolder of /app/public/branding|footage|applications|cases|news|
parts|operations-inbox|heritage on each container start, fixing any
files that previously slipped through with the wrong group. Single
fast pass, idempotent. Adds /app/public/heritage to the list (was
missing).

3) AUTO-CREATE ASSET BUCKETS on entity create
The big editor UX win: when an admin creates a Case (GlobalNode), an
Application or a News article in HQ Command, the server now also
mkdir's the well-known asset subfolders for that entity. So after
creating "Acme Industries" as a case, the editor immediately gets
/public/cases/acme-industries/{videos,renders,gallery,datasheet,models}
ready — no more "EACCES because the dir wasn't created" gotcha
when they upload their first video.

Implementation:
- src/lib/assetFolders.ts: typed helper with per-scope bucket lists
  + a titleToSlug helper that mirrors the front-end's slugger so the
  folder name matches what ApplicationClient expects when rendering
  /cases/<slug>/videos/<file>.
- network/actions.ts: createNode -> ensureAssetFolders("cases", slug).
  Plus a new server action ensureNodeAssetFolders(id) so the editor
  can fix existing nodes without recreating them (one-click "Repair").
- news/actions.ts: createNewsArticle -> ensureAssetFolders("news",slug)
- applications/actions.ts: createApplication -> ensureAssetFolders(...)

DEPLOY (David)
  cd /opt/flux-srl
  git pull
  docker compose up -d --build app
  # The entrypoint will fix existing 1001:65533 files automatically
  # as the container boots — no manual chown needed.

src/lib/assetFolders.ts

@@ -0,0 +1,72 @@
+// src/lib/assetFolders.ts
+// ─────────────────────────────────────────────────────────────────────────────
+// Server-side helpers that ensure every asset bucket exists when an editor
+// creates a new entity in HQ Command. Without this, the editor's first
+// upload error-paths because the target subfolder doesn't exist yet.
+//
+// Each scope has a known set of "buckets" — the well-known subfolder layout
+// the front-end expects (e.g. cases use videos/, renders/, gallery/). We
+// pre-create them all so editors can drop files anywhere without needing
+// to think about server-side folder structure.
+// ─────────────────────────────────────────────────────────────────────────────
+
+import "server-only";
+import fs from "fs";
+import path from "path";
+
+export type AssetScope = "cases" | "applications" | "news" | "parts";
+
+const SCOPE_ROOT: Record<AssetScope, string> = {
+  cases: path.join(process.cwd(), "public", "cases"),
+  applications: path.join(process.cwd(), "public", "applications"),
+  news: path.join(process.cwd(), "public", "news"),
+  parts: path.join(process.cwd(), "public", "parts"),
+};
+
+// Buckets per scope — the subfolders the front-end reads from.
+// Adding a new bucket here is the only place in the codebase you need to
+// touch to introduce a new asset type.
+const SCOPE_BUCKETS: Record<AssetScope, string[]> = {
+  cases: ["videos", "renders", "gallery", "datasheet", "models"],
+  applications: ["videos", "renders", "gallery", "datasheet"],
+  news: ["gallery"],
+  parts: ["renders", "gallery"],
+};
+
+/**
+ * Create the slug folder + every bucket subfolder if they don't exist.
+ * Idempotent — safe to call on every entity create or edit.
+ */
+export function ensureAssetFolders(scope: AssetScope, slug: string): void {
+  if (!slug) return;
+
+  try {
+    const safeSlug = slug.toLowerCase().replace(/[^a-z0-9_-]/g, "-").replace(/-+/g, "-").replace(/^-|-$/g, "");
+    if (!safeSlug) return;
+
+    const root = SCOPE_ROOT[scope];
+    const baseDir = path.join(root, safeSlug);
+
+    fs.mkdirSync(baseDir, { recursive: true });
+
+    for (const bucket of SCOPE_BUCKETS[scope]) {
+      fs.mkdirSync(path.join(baseDir, bucket), { recursive: true });
+    }
+  } catch (error) {
+    console.error(`[assetFolders] Failed to ensure ${scope}/${slug}:`, error);
+  }
+}
+
+/**
+ * Convert a free-text title into the same slug the front-end uses.
+ * Mirrors `nodeToSlug` in ApplicationClient.tsx so the folder name matches
+ * the path the page renders for that node's assets.
+ */
+export function titleToSlug(title: string): string {
+  return title
+    .toLowerCase()
+    .trim()
+    .replace(/[^\w\s-]/g, "")
+    .replace(/[\s_-]+/g, "-")
+    .replace(/^-+|-+$/g, "");
+}