fix: resolve category delegation and command routing with display name agent keys

Category-based delegation (task(category='quick')) was broken because
SISYPHUS_JUNIOR_AGENT sent 'sisyphus-junior' to session.prompt but
config.agent keys are now display names ('Sisyphus-Junior').

- Use getAgentDisplayName() for SISYPHUS_JUNIOR_AGENT constant
- Replace hardcoded 'sisyphus-junior' strings in tools.ts with constant
- Update background-output local constants to use display names
- Add remapCommandAgentFields() to translate command agent fields
- Add raw-key fallback in tool-config-handler agentByKey()

src/plugin-handlers/tool-config-handler.ts

@@ -4,7 +4,9 @@ import { getAgentDisplayName } from "../shared/agent-display-names";
 type AgentWithPermission = { permission?: Record<string, unknown> };
 
 function agentByKey(agentResult: Record<string, unknown>, key: string): AgentWithPermission | undefined {
-  return agentResult[getAgentDisplayName(key)] as AgentWithPermission | undefined;
+  return (agentResult[key] ?? agentResult[getAgentDisplayName(key)]) as
+    | AgentWithPermission
+    | undefined;
 }
 
 export function applyToolConfig(params: {