feat: implement account recovery with encrypted backup bundles

Add recovery code generation (8 codes per setup), Argon2id key derivation,
ChaCha20-Poly1305 encrypted bundles, and server-side zero-knowledge storage.
Each code independently recovers the account. Includes core crypto module,
protobuf service (method IDs 750-752), server domain + handlers, SDK methods,
SQL migration, and CLI commands (/recovery setup, /recovery restore).

crates/quicproquo-client/src/v2_main.rs

@@ -122,6 +122,18 @@ enum Cmd {
         #[command(subcommand)]
         action: DevicesCmd,
     },
+
+    /// Account recovery management.
+    Recovery {
+        #[command(subcommand)]
+        action: RecoveryCmd,
+    },
+
+    /// Offline outbox management.
+    Outbox {
+        #[command(subcommand)]
+        action: OutboxCmd,
+    },
 }
 
 #[derive(Debug, Subcommand)]
@@ -163,6 +175,27 @@ enum DevicesCmd {
     },
 }
 
+#[derive(Debug, Subcommand)]
+enum RecoveryCmd {
+    /// Generate recovery codes and upload encrypted bundles.
+    Setup,
+    /// Recover account from a recovery code.
+    Restore {
+        /// Recovery code (e.g. "A3B7K9").
+        code: String,
+    },
+}
+
+#[derive(Debug, Subcommand)]
+enum OutboxCmd {
+    /// Show pending outbox entries.
+    List,
+    /// Retry sending all pending outbox entries.
+    Retry,
+    /// Clear permanently failed outbox entries.
+    Clear,
+}
+
 // ── Auto-server launch ───────────────────────────────────────────────────────
 
 /// RAII guard that kills an auto-started server process on drop.
@@ -481,6 +514,49 @@ async fn run(args: Args) -> anyhow::Result<()> {
                 .await
                 .context("device revoke failed")?;
         }
+
+        Cmd::Recovery {
+            action: RecoveryCmd::Setup,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_recovery_setup(&mut client)
+                .await
+                .context("recovery setup failed")?;
+        }
+
+        Cmd::Recovery {
+            action: RecoveryCmd::Restore { ref code },
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_recovery_restore(&mut client, code)
+                .await
+                .context("recovery restore failed")?;
+        }
+
+        Cmd::Outbox {
+            action: OutboxCmd::List,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_outbox_list(&client)
+                .context("outbox list failed")?;
+        }
+
+        Cmd::Outbox {
+            action: OutboxCmd::Retry,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_outbox_retry(&mut client)
+                .await
+                .context("outbox retry failed")?;
+        }
+
+        Cmd::Outbox {
+            action: OutboxCmd::Clear,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_outbox_clear(&client)
+                .context("outbox clear failed")?;
+        }
     }
 
     Ok(())