feat(cli): clap surface for backup export/restore (handlers stubbed)

Adds 'relicario backup' as a subcommand wrapping export and restore.
Stubs return 'not yet implemented' — handlers land in Tasks 8 and 9.
The existing top-level 'relicario restore <query>' (un-trash) is
untouched.

crates/relicario-cli/src/main.rs

@@ -94,6 +94,12 @@ enum Commands {
         action: TrashAction,
     },
 
+    /// Backup operations: pack and unpack `.relbak` archives.
+    Backup {
+        #[command(subcommand)]
+        action: BackupAction,
+    },
+
     /// Attach a file to an item.
     Attach { query: String, file: PathBuf },
 
@@ -274,6 +280,35 @@ enum DeviceAction {
     Revoke { name: String },
 }
 
+#[derive(Subcommand)]
+enum BackupAction {
+    /// Pack the local vault into a single encrypted `.relbak` file.
+    /// Backup passphrase is independent of the vault passphrase.
+    Export {
+        /// Output `.relbak` path.
+        out: PathBuf,
+        /// Bundle the reference JPEG into the encrypted envelope.
+        #[arg(long)]
+        include_image: bool,
+        /// Override the reference image path (defaults to the vault's
+        /// `reference.jpg` or `RELICARIO_IMAGE`).
+        #[arg(long)]
+        image: Option<PathBuf>,
+        /// Skip bundling `.git/` history.
+        #[arg(long)]
+        no_history: bool,
+    },
+    /// Unpack a `.relbak` file into a fresh vault directory.
+    Restore {
+        /// Input `.relbak` path.
+        input: PathBuf,
+        /// Target directory (must NOT already contain `.relicario/`).
+        /// Defaults to the current directory.
+        #[arg(default_value = ".")]
+        target: PathBuf,
+    },
+}
+
 fn main() -> Result<()> {
     let cli = Cli::parse();
     match cli.command {
@@ -287,6 +322,7 @@ fn main() -> Result<()> {
         Commands::Restore { query } => cmd_restore(query),
         Commands::Purge { query } => cmd_purge(query),
         Commands::Trash { action } => cmd_trash(action),
+        Commands::Backup { action } => cmd_backup(action),
         Commands::Attach { query, file } => cmd_attach(query, file),
         Commands::Attachments { query } => cmd_attachments(query),
         Commands::Extract { query, aid, out } => cmd_extract(query, aid, out),
@@ -1243,6 +1279,28 @@ fn cmd_trash(action: TrashAction) -> Result<()> {
     }
 }
 
+fn cmd_backup(action: BackupAction) -> Result<()> {
+    match action {
+        BackupAction::Export { out, include_image, image, no_history } => {
+            cmd_backup_export(out, include_image, image, no_history)
+        }
+        BackupAction::Restore { input, target } => cmd_backup_restore(input, target),
+    }
+}
+
+fn cmd_backup_export(
+    _out: PathBuf,
+    _include_image: bool,
+    _image: Option<PathBuf>,
+    _no_history: bool,
+) -> Result<()> {
+    anyhow::bail!("cmd_backup_export not yet implemented")
+}
+
+fn cmd_backup_restore(_input: PathBuf, _target: PathBuf) -> Result<()> {
+    anyhow::bail!("cmd_backup_restore not yet implemented")
+}
+
 fn cmd_trash_empty() -> Result<()> {
     use relicario_core::time::now_unix;