feat(pages): configurable limits, multi-format packages, and dual versioning

Make Pages package size and history retention system-configurable, support
zip/tar.gz/tar.xz/tar.bz2/tar/7z uploads, prune history with clear keep-N
semantics, and rebind agent config to the live active Pages deployment so
main-config rollback never depends on pruned packages.

pkg/pagesarchive/path.go

@@ -0,0 +1,85 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package pagesarchive
+
+import (
+	"fmt"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+// NormalizeEntryPath cleans an archive entry path and rejects zip-slip / absolute paths.
+// skip=true means the entry should be ignored (empty path or directory marker).
+func NormalizeEntryPath(raw string) (cleaned string, skip bool, err error) {
+	name := strings.TrimSpace(filepath.ToSlash(raw))
+	if name == "" {
+		return "", true, nil
+	}
+	if strings.HasSuffix(name, "/") {
+		return "", true, nil
+	}
+	if strings.HasPrefix(name, "/") || path.IsAbs(name) {
+		return "", false, fmt.Errorf("pages package contains absolute path: %s", raw)
+	}
+	// Reject Windows drive / UNC-style paths that may appear after ToSlash.
+	if len(name) >= 2 && name[1] == ':' {
+		return "", false, fmt.Errorf("pages package contains absolute path: %s", raw)
+	}
+	cleanedPath := path.Clean(name)
+	if cleanedPath == "." {
+		return "", true, nil
+	}
+	if cleanedPath == ".." || strings.HasPrefix(cleanedPath, "../") || strings.Contains(cleanedPath, "/../") {
+		return "", false, fmt.Errorf("pages package path escapes directory: %s", raw)
+	}
+	return cleanedPath, false, nil
+}
+
+// FindCommonRootPrefix returns a trailing-slash directory prefix shared by all file paths.
+// When files do not share a single root folder the result is empty.
+func FindCommonRootPrefix(paths []string) string {
+	var firstFilePath string
+	hasMultipleFiles := false
+	for _, item := range paths {
+		normalizedPath, skip, err := NormalizeEntryPath(item)
+		if err != nil || skip {
+			continue
+		}
+		if firstFilePath == "" {
+			firstFilePath = normalizedPath
+		} else {
+			hasMultipleFiles = true
+		}
+	}
+	if firstFilePath == "" {
+		return ""
+	}
+	parts := strings.Split(firstFilePath, "/")
+	if len(parts) <= 1 {
+		return ""
+	}
+	commonPrefix := parts[0] + "/"
+	if !hasMultipleFiles {
+		return commonPrefix
+	}
+	for _, item := range paths {
+		normalizedPath, skip, err := NormalizeEntryPath(item)
+		if err != nil || skip {
+			continue
+		}
+		if !strings.HasPrefix(normalizedPath, commonPrefix) {
+			return ""
+		}
+	}
+	return commonPrefix
+}
+
+// StripPrefix removes a directory prefix from a cleaned path when present.
+func StripPrefix(normalizedPath, prefix string) string {
+	if prefix == "" {
+		return normalizedPath
+	}
+	return strings.TrimPrefix(normalizedPath, prefix)
+}