feat(orchestration): add bttask CLI + GroupAgentsPanel + btmsg Tauri bridge

Phase 2: bttask CLI (Python, SQLite) — task management with role-based
visibility. Kanban board view. Manager/Architect can create tasks,
Tier 2 agents receive tasks via btmsg only.

Phase 3: GroupAgentConfig in groups.json + Rust backend. GroupAgentsPanel
Svelte component above ProjectGrid with status dots, role icons,
unread badges, start/stop buttons.

Phase 4: btmsg Rust bridge (btmsg.rs) — read/write access to btmsg.db.
6 Tauri commands for agent status, messages, and history.
GroupAgentsPanel polls btmsg.db every 5s for live status updates.

v2/src-tauri/src/commands/btmsg.rs

@@ -0,0 +1,31 @@
+use crate::btmsg;
+
+#[tauri::command]
+pub fn btmsg_get_agents(group_id: String) -> Result<Vec<btmsg::BtmsgAgent>, String> {
+    btmsg::get_agents(&group_id)
+}
+
+#[tauri::command]
+pub fn btmsg_unread_count(agent_id: String) -> Result<i32, String> {
+    btmsg::unread_count(&agent_id)
+}
+
+#[tauri::command]
+pub fn btmsg_unread_messages(agent_id: String) -> Result<Vec<btmsg::BtmsgMessage>, String> {
+    btmsg::unread_messages(&agent_id)
+}
+
+#[tauri::command]
+pub fn btmsg_history(agent_id: String, other_id: String, limit: i32) -> Result<Vec<btmsg::BtmsgMessage>, String> {
+    btmsg::history(&agent_id, &other_id, limit)
+}
+
+#[tauri::command]
+pub fn btmsg_send(from_agent: String, to_agent: String, content: String) -> Result<String, String> {
+    btmsg::send_message(&from_agent, &to_agent, &content)
+}
+
+#[tauri::command]
+pub fn btmsg_set_status(agent_id: String, status: String) -> Result<(), String> {
+    btmsg::set_status(&agent_id, &status)
+}

v2/src-tauri/src/commands/mod.rs

@@ -9,3 +9,4 @@ pub mod groups;
 pub mod files;
 pub mod remote;
 pub mod misc;
+pub mod btmsg;