feat(a2a): register list-capabilities in A2A_SKILL_HANDLERS + Agent Card

Adds "list-capabilities" entry to A2A_SKILL_HANDLERS in taskExecution.ts
(dynamic import pattern, consistent with the 5 existing skills) and adds
the 6th skill entry to /.well-known/agent.json with tags [discovery, capabilities]
and example questions for agent discovery.

src/app/.well-known/agent.json/route.ts

@@ -102,6 +102,15 @@ export async function GET() {
           "Summarize active rate limits and lockouts",
         ],
       },
+      {
+        id: "list-capabilities",
+        name: "List Capabilities",
+        description:
+          "Returns the full catalog of 42 OmniRoute agent skills (22 API + 20 CLI) " +
+          "with raw URLs for the SKILL.md docs.",
+        tags: ["discovery", "capabilities"],
+        examples: ["What can you do?", "List your skills", "Show capabilities"],
+      },
     ],
     authentication: {
       schemes: ["api-key"],

src/lib/a2a/taskExecution.ts

@@ -37,6 +37,10 @@ export const A2A_SKILL_HANDLERS: Record<string, A2ASkillHandler> = {
     const skillModule = await import("./skills/healthReport");
     return skillModule.executeHealthReport(task);
   },
+  "list-capabilities": async (task) => {
+    const skillModule = await import("./skills/listCapabilities");
+    return skillModule.executeListCapabilities(task);
+  },
 };
 
 export async function executeA2ATaskWithState(