refactor: ApprovalKind::as_str owns the kind→string mapping

replaces three hand-rolled six-arm matches (actions.rs ×2,
state_snapshot.rs); approvals::kind_to_str delegates. a new kind can
no longer silently miss one of them

hive-c0re/src/dashboard/state_snapshot.rs

@@ -526,14 +526,7 @@ fn history_view(a: Approval) -> ApprovalHistoryView {
         // Pending shouldn't appear in recent_resolved, but be defensive.
         hive_sh4re::ApprovalStatus::Pending => "pending",
     };
-    let kind = match a.kind {
-        hive_sh4re::ApprovalKind::ApplyCommit => "apply_commit",
-        hive_sh4re::ApprovalKind::Spawn => "spawn",
-        hive_sh4re::ApprovalKind::InitConfig => "init_config",
-        hive_sh4re::ApprovalKind::UpdateMetaInputs => "update_meta_inputs",
-        hive_sh4re::ApprovalKind::SchedulePrompt => "schedule_prompt",
-        hive_sh4re::ApprovalKind::MergeConfigPr => "merge_config_pr",
-    };
+    let kind = a.kind.as_str();
     ApprovalHistoryView {
         id: a.id,
         agent: a.agent,