fix(agents): restore canonical core agent ordering

Remap the core agent keys, default agent, and command routing back to\nlist display names so OpenCode's name-based sorting keeps the\ncanonical Sisyphus -> Hephaestus -> Prometheus -> Atlas order.\n\nAlso teach tool config lookups to resolve the prefixed list keys and\nadd regression tests that exercise the real ordering and routing path.

src/plugin-handlers/agent-key-remapper.ts

@@ -1,4 +1,4 @@
-import { getAgentDisplayName } from "../shared/agent-display-names"
+import { getAgentListDisplayName } from "../shared/agent-display-names"
 
 export function remapAgentKeysToDisplayNames(
   agents: Record<string, unknown>,
@@ -6,7 +6,7 @@ export function remapAgentKeysToDisplayNames(
   const result: Record<string, unknown> = {}
 
   for (const [key, value] of Object.entries(agents)) {
-    const displayName = getAgentDisplayName(key)
+    const displayName = getAgentListDisplayName(key)
     if (displayName && displayName !== key) {
       result[displayName] = value
       // Regression guard: do not also assign result[key].