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.

uninstall.sh

@@ -0,0 +1,78 @@
+#!/bin/bash
+# uninstall.sh — removes all traces of the patch from a TrueNAS box.
+
+set -euo pipefail
+
+PATCH_DIR="/data/truecloud-patch"
+
+echo "=== TrueNAS TrueCloud Provider Patch — Uninstall ==="
+echo ""
+
+if ! command -v midclt &>/dev/null; then
+    echo "ERROR: midclt not found. Run this script on TrueNAS SCALE." >&2
+    exit 1
+fi
+
+# ── Remove PREINIT registration ───────────────────────────────────────────────
+IDS=$(midclt call initshutdownscript.query '[]' | \
+    python3 -c "
+import sys, json
+for s in json.load(sys.stdin):
+    if s.get('script') == '/data/truecloud-patch/apply.sh':
+        print(s['id'])
+" 2>/dev/null || true)
+
+if [ -n "$IDS" ]; then
+    for id in $IDS; do
+        midclt call initshutdownscript.delete "$id" > /dev/null
+        echo "Removed initshutdownscript id=$id"
+    done
+else
+    echo "No initshutdownscript entry found (already removed or never installed)."
+fi
+echo ""
+
+# ── Remove sitecustomize.py ───────────────────────────────────────────────────
+SITE_PKG=$(python3 -c "import site; print(site.getsitepackages()[0])" 2>/dev/null || true)
+
+if [ -n "$SITE_PKG" ] && [ -f "$SITE_PKG/sitecustomize.py" ]; then
+    if grep -q "truecloud-patch" "$SITE_PKG/sitecustomize.py" 2>/dev/null; then
+        rm "$SITE_PKG/sitecustomize.py"
+        echo "Removed $SITE_PKG/sitecustomize.py"
+
+        # Restore a pre-existing sitecustomize.py if we backed one up
+        if [ -f "$SITE_PKG/sitecustomize.py.pre-truecloud-patch" ]; then
+            mv "$SITE_PKG/sitecustomize.py.pre-truecloud-patch" \
+               "$SITE_PKG/sitecustomize.py"
+            echo "Restored previous sitecustomize.py"
+        fi
+    fi
+fi
+echo ""
+
+# ── Restore UI bundle backup ──────────────────────────────────────────────────
+RESTORED=0
+for backup in $(find /usr/share/truenas /var/www/truenas -name "*.js.pre-truecloud-patch" 2>/dev/null); do
+    original="${backup%.pre-truecloud-patch}"
+    mv "$backup" "$original"
+    echo "Restored: $original"
+    RESTORED=1
+done
+
+if [ "$RESTORED" -eq 0 ]; then
+    echo "No UI bundle backups found (patch will be undone by the next TrueNAS update)."
+fi
+echo ""
+
+# ── Remove patch directory ────────────────────────────────────────────────────
+if [ -d "$PATCH_DIR" ]; then
+    rm -rf "$PATCH_DIR"
+    echo "Removed $PATCH_DIR"
+fi
+echo ""
+
+echo "Restarting middlewared ..."
+systemctl restart middlewared
+
+echo ""
+echo "Uninstall complete. Refresh your browser to see the restored UI."