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/command-config-handler.ts

@@ -1,4 +1,5 @@
 import type { OhMyOpenCodeConfig } from "../config";
+import { getAgentDisplayName } from "../shared/agent-display-names";
 import {
   loadUserCommands,
   loadProjectCommands,
@@ -68,4 +69,14 @@ export async function applyCommandConfig(params: {
     ...params.pluginComponents.commands,
     ...params.pluginComponents.skills,
   };
+
+  remapCommandAgentFields(params.config.command as Record<string, Record<string, unknown>>);
+}
+
+function remapCommandAgentFields(commands: Record<string, Record<string, unknown>>): void {
+  for (const cmd of Object.values(commands)) {
+    if (cmd?.agent && typeof cmd.agent === "string") {
+      cmd.agent = getAgentDisplayName(cmd.agent);
+    }
+  }
 }