feat(mobile): per-user device bindings, multi-user Inbox routing, and admin-mediated authorization

- Device→user bindings persisted in config table (auth.rs), loaded at plugin start
- RelayApp now routes Inbox responses per-user via UserChannelApi, never globally
- New mobile_bind_device LLM tool for admin-mediated device→user assignment
- Per-user event forwarders (events.rs) with per-user debounced notifiers
- Config listener (auth::config_listener) refreshes bindings cache reactively
- Reconcile loop catches users who unlock after boot
- Hello/Logout treated as device-registry ops (no user resolution needed)
- Unbound device payloads are silently dropped
- RelayAgent::authorize_client → bind_device (atomic bind + authorize)
- Approval rules seed mobile_bind_device/revoke_device as require

crates/plugin-mobile-connector/src/tools.rs

@@ -19,6 +19,7 @@ use crate::agent::{ClientState, RelayAgent};
 /// Tool name constants (also the patterns the host uses for approval rules).
 pub const TOOL_START_PAIRING: &str = "mobile_start_pairing";
 pub const TOOL_LIST_DEVICES: &str = "mobile_list_devices";
+pub const TOOL_BIND_DEVICE: &str = "mobile_bind_device";
 pub const TOOL_REVOKE_DEVICE: &str = "mobile_revoke_device";
 
 /// Build the plugin's LLM tools, bound to a `RelayAgent`. The host calls this
@@ -27,6 +28,7 @@ pub fn mobile_tools(agent: Arc<dyn RelayAgent>) -> Vec<Arc<dyn Tool>> {
     vec![
         Arc::new(StartPairingTool { agent: Arc::clone(&agent) }),
         Arc::new(ListDevicesTool { agent: Arc::clone(&agent) }),
+        Arc::new(BindDeviceTool { agent: Arc::clone(&agent) }),
         Arc::new(RevokeDeviceTool { agent }),
     ]
 }
@@ -82,7 +84,8 @@ struct ListDevicesTool {
 impl Tool for ListDevicesTool {
     fn name(&self) -> &str { TOOL_LIST_DEVICES }
     fn description(&self) -> &str {
-        "List paired mobile devices: state (pending/authorized), platform, device info, last seen."
+        "List paired mobile devices: state (pending/authorized), bound user, platform, device info, last seen. \
+         Use the `ed25519_pub` of a pending device with mobile_bind_device to assign it to a user."
     }
     fn parameters_schema(&self) -> Value {
         json!({ "type": "object", "properties": {} })
@@ -109,6 +112,7 @@ impl Tool for ListDevicesTool {
                             ClientState::Authorized => "authorized",
                             ClientState::Pending => "pending",
                         },
+                        "bound_user": c.bound_user,
                         "platform": c.platform,
                         "device_info": device_info,
                         "last_seen": c.last_seen,
@@ -120,6 +124,63 @@ impl Tool for ListDevicesTool {
     }
 }
 
+// ── mobile_bind_device ────────────────────────────────────────────────────────
+
+struct BindDeviceTool {
+    agent: Arc<dyn RelayAgent>,
+}
+
+impl Tool for BindDeviceTool {
+    fn name(&self) -> &str { TOOL_BIND_DEVICE }
+    fn description(&self) -> &str {
+        "Bind a paired mobile device to a Skald user and authorize it. The device then \
+         receives that user's Inbox (approvals/clarifications/elicitations) and push \
+         notifications — and only that user's. Requires user approval."
+    }
+    fn parameters_schema(&self) -> Value {
+        json!({
+            "type": "object",
+            "properties": {
+                "pubkey": {
+                    "type": "string",
+                    "description": "The device's ed25519 public key, hex-encoded (64 chars), from mobile_list_devices."
+                },
+                "user_id": {
+                    "type": "string",
+                    "description": "The Skald user id to bind this device to."
+                },
+                "display": {
+                    "type": "string",
+                    "description": "Optional human-friendly label for the binding."
+                }
+            },
+            "required": ["pubkey", "user_id"]
+        })
+    }
+    fn category(&self) -> ToolCategory { ToolCategory::Config }
+
+    fn execute_async<'a>(
+        &'a self,
+        args: Value,
+    ) -> std::pin::Pin<Box<dyn std::future::Future<Output = Result<String>> + Send + 'a>> {
+        Box::pin(async move {
+            let pubkey = args
+                .get("pubkey")
+                .and_then(Value::as_str)
+                .ok_or_else(|| anyhow::anyhow!("mobile_bind_device: missing `pubkey`"))?;
+            let user_id = args
+                .get("user_id")
+                .and_then(Value::as_str)
+                .ok_or_else(|| anyhow::anyhow!("mobile_bind_device: missing `user_id`"))?;
+            let display = args.get("display").and_then(Value::as_str).map(str::to_string);
+            let ed = skald_relay_common::crypto::decode_hex::<32>(pubkey)
+                .ok_or_else(|| anyhow::anyhow!("mobile_bind_device: `pubkey` is not 32-byte hex"))?;
+            self.agent.bind_device(ed, user_id.to_string(), display).await?;
+            Ok(format!("Device {pubkey} bound to user {user_id} and authorized."))
+        })
+    }
+}
+
 // ── mobile_revoke_device ──────────────────────────────────────────────────────
 
 struct RevokeDeviceTool {
@@ -129,7 +190,8 @@ struct RevokeDeviceTool {
 impl Tool for RevokeDeviceTool {
     fn name(&self) -> &str { TOOL_REVOKE_DEVICE }
     fn description(&self) -> &str {
-        "Revoke a paired mobile device by its ed25519 public key (hex). The device loses access immediately."
+        "Revoke a paired mobile device by its ed25519 public key (hex) and drop its user binding. \
+         The device loses access immediately."
     }
     fn parameters_schema(&self) -> Value {
         json!({