fix(core): resolve all 12 adversarial review findings

- Zeroize passwords in CLI prompts, handlers, and mount authentication
- Preserve carrier_node_id when recovering Slot 0 via recovery key
- Add --slot parameter to restore-header for targeted slot recovery
- Implement online_backup and restore_from_backup using SQLite Online Backup API
- Expose 'sanctum backup' and 'sanctum restore' CLI subcommands
- Fix inactivity auto-lock by removing touch() from PROPFIND metadata/read_dir
- Support O_APPEND by setting file cursor to file size on handle creation
- Prevent data loss by implementing Drop for CarrierFile to flush dirty blocks
- Optimize CSPRNG padding to only fill unwritten slack space
- Batch carrier initialization in 500-block transactions to prevent UI/CLI freeze
- Enforce 64-byte savings threshold for LZ4 compression
- Add WebClient service diagnostic hint for Windows net use mount errors
- Add unit and integration tests covering all new features

src/mount.rs

@@ -13,6 +13,7 @@ use hyper_util::rt::TokioIo;
 use tokio::net::TcpListener;
 use tokio::sync::watch;
 use tracing::{debug, warn};
+use zeroize::Zeroizing;
 
 use crate::crypto::mnemonic_to_dek;
 use crate::storage::Database;
@@ -22,8 +23,8 @@ use crate::vfs::SanctumFs;
 /// Authentifizierungsmethode für das Einbinden eines Containers: Entweder Master-Passwort oder 24-Wort Notfallschlüssel.
 #[derive(Debug, Clone)]
 pub enum ContainerAuth {
-    Password(String),
-    RecoveryKey(String),
+    Password(Zeroizing<String>),
+    RecoveryKey(Zeroizing<String>),
 }
 
 /// Hilfsfunktion zur Formatierung des Laufwerksbuchstabens (z. B. 'S' -> "S:")
@@ -66,11 +67,17 @@ fn run_net_use_mount(drive_str: &str, port: u16) -> Result<()> {
     if !output.status.success() {
         let stderr = String::from_utf8_lossy(&output.stderr);
         let stdout = String::from_utf8_lossy(&output.stdout);
+        let webclient_hint = if stderr.contains("67") || stderr.contains("Netzwerkname") || stderr.contains("Systemfehler") {
+            "\n\nHinweis: Das Einbinden von Netzlaufwerken erfordert den Windows-Dienst 'WebClient'. Prüfen Sie in einer Administrator-Konsole: 'net start WebClient'."
+        } else {
+            ""
+        };
         bail!(
-            "Laufwerk {} konnte nicht eingebunden werden:\n{}{}",
+            "Laufwerk {} konnte nicht eingebunden werden:\n{}{}{}",
             drive_str,
             stdout,
-            stderr
+            stderr,
+            webclient_hint
         );
     }