Initial implementation: extend TrueCloud Backup to S3 and B2 providers

Patches middlewared at runtime via sitecustomize.py (no file edits to /usr/)
and widens the UI credential dropdown from Storj-only to S3+B2+Storj.
Persists across TrueNAS updates via PREINIT initshutdownscript stored in DB.

install.sh

@@ -0,0 +1,74 @@
+#!/bin/bash
+# install.sh — run once on the TrueNAS box to set up the patch.
+#
+# What this does:
+#   1. Copies patch files to /data/truecloud-patch/ (survives updates).
+#   2. Registers a PREINIT initshutdownscript so apply.sh runs on every boot
+#      before middlewared starts, re-applying patches to the refreshed /usr/.
+#   3. Applies the patches immediately without rebooting.
+#   4. Restarts middlewared so the backend patch takes effect now.
+
+set -euo pipefail
+
+PATCH_DIR="/data/truecloud-patch"
+REPO_DIR="$(cd "$(dirname "$0")" && pwd)"
+
+echo "=== TrueNAS TrueCloud Provider Patch ==="
+echo ""
+
+if ! command -v midclt &>/dev/null; then
+    echo "ERROR: midclt not found. Run this script on TrueNAS SCALE." >&2
+    exit 1
+fi
+
+# ── Copy files ────────────────────────────────────────────────────────────────
+echo "Copying patch files to $PATCH_DIR ..."
+mkdir -p "$PATCH_DIR"
+cp "$REPO_DIR/patch/sitecustomize.py" "$PATCH_DIR/"
+cp "$REPO_DIR/patch/patch_ui.py"      "$PATCH_DIR/"
+cp "$REPO_DIR/patch/apply.sh"         "$PATCH_DIR/"
+cp "$REPO_DIR/patch/create_task.py"   "$PATCH_DIR/"
+chmod +x "$PATCH_DIR/apply.sh" "$PATCH_DIR/create_task.py"
+echo "Done."
+echo ""
+
+# ── Register PREINIT script ───────────────────────────────────────────────────
+echo "Checking initshutdownscript registration ..."
+
+EXISTING_ID=$(midclt call initshutdownscript.query '[]' | \
+    python3 -c "
+import sys, json
+for s in json.load(sys.stdin):
+    if s.get('script') == '/data/truecloud-patch/apply.sh':
+        print(s['id'])
+        break
+" 2>/dev/null || true)
+
+if [ -n "$EXISTING_ID" ]; then
+    echo "Already registered (id=$EXISTING_ID). Ensuring it is enabled ..."
+    midclt call initshutdownscript.update "$EXISTING_ID" \
+        '{"enabled": true}' > /dev/null
+else
+    midclt call initshutdownscript.create \
+        '{"type":"SCRIPT","script":"/data/truecloud-patch/apply.sh","when":"PREINIT","enabled":true,"comment":"TrueCloud provider patch (S3/B2)"}' \
+        > /dev/null
+    echo "Registered PREINIT script."
+fi
+echo ""
+
+# ── Apply now ─────────────────────────────────────────────────────────────────
+echo "Applying patches ..."
+bash "$PATCH_DIR/apply.sh"
+cat "$PATCH_DIR/apply.log" | tail -20
+echo ""
+
+# ── Restart middlewared ───────────────────────────────────────────────────────
+echo "Restarting middlewared (backend patch takes effect) ..."
+systemctl restart middlewared
+echo "Done."
+echo ""
+
+echo "Refresh your browser to pick up the UI change."
+echo ""
+echo "To create a TrueCloud Backup task with S3 or B2 credentials:"
+echo "  python3 $PATCH_DIR/create_task.py --help"