feat(bd-4s6): add bv triage commands for recommendations

Implements get_triage and get_next_pick Tauri commands that call
bv --robot-triage and bv --robot-next respectively.

Response types are frontend-friendly (specta::Type) with:
- TriageResponse: counts, top_picks, quick_wins, blockers_to_clear
- NextPickResponse: single best pick with claim_command

Includes 5 tests covering:
- Structured data transformation
- Empty list handling
- Error propagation (BvUnavailable, BvTriageFailed)

src-tauri/src/lib.rs

@@ -121,6 +121,11 @@ pub fn run() {
         commands::read_state,
         commands::write_state,
         commands::clear_state,
+        commands::get_triage,
+        commands::get_next_pick,
+        commands::close_bead,
+        commands::log_decision,
+        commands::update_item,
     ]);
 
     // Export TypeScript bindings in debug builds