Webapp: Updates pages, image page tabs with review-before-save, BPRT sync

Updates group:
- Dell drivers and BIOS: check Dell's catalogs against all three driver maps
  and models.txt, download with a shared speed cap, repack, preview, apply
  with backups and rollback.
- iPXE boot files: check GitHub for the signed Secure Boot set, verify the
  sha256 and each file's signer, install atomically, roll back. Includes the
  by-hand procedure.
- Blancco: upload a release, stage it, test-boot it from the menu, activate,
  roll back.
- BPRT sync: validate a batch uploaded from the MediaCreator Lite cache
  (scripts/windows/Sync-BPRT.ps1 or a zip), show the diff, swap with the site
  overlay files kept.

Images: one sidebar entry per image with Overview, Drivers, Unattend and OS and
Packages tabs. Every save shows a diff first, keeps the file's format, makes a
backup and can be undone. Driver lint runs inline.

Enrollment: upload standard/engineer MCL packages, one per tenant/purpose,
with archive and restore. Hardware coverage counts engineer as Win11.

webapp/views/__init__.py

@@ -0,0 +1,37 @@
+"""Feature blueprints registered by app.py (one module per page group).
+
+    views.dell_updates   - Updates > Dell drivers and BIOS
+    views.ipxe           - Updates > iPXE Secure Boot files
+    views.blancco_update - Updates > Blancco Drive Eraser releases
+
+Shared here: the download speed cap form handler. The cap is one setting
+(services/updates_common.py settings.json) used by every download; each
+Updates page with downloads shows the same form and posts it to its own
+route, which calls save_speed_cap() and redirects back to that page.
+"""
+
+import math
+
+from flask import flash, request
+
+from services import updates_common
+from services.audit import audit
+
+
+def save_speed_cap():
+    """Validate and save the shared speed cap from the posted form, audit and
+    flash the result. Returns the saved settings, or None when refused."""
+    try:
+        value = float(request.form.get("max_mbps", ""))
+        if not math.isfinite(value):  # float() accepts "nan"
+            raise ValueError("not a number")
+        data = updates_common.save_settings(value)
+    except ValueError as ex:
+        msg = str(ex) if "between" in str(ex) else "enter a number of MB/s (0 = no cap)"
+        flash(f"Speed cap not saved: {msg}", "danger")
+        return None
+    audit("UPDATES_SPEED_CAP", f"{data['max_mbps']} MB/s")
+    cap = data["max_mbps"]
+    flash(f"Download speed cap set to {cap:g} MB/s (shared by Dell and iPXE downloads)."
+          if cap else "Download speed cap removed (shared by Dell and iPXE downloads).", "success")
+    return data