feat(FN-2709): migrate Hermes runtime plugin to pi-ai streaming client

- Replace Hermes pi module integration with pi-ai session streaming and updated runtime adapter contracts
- Remove legacy engine guard scaffolding and add hermes-stream-client coverage for streaming behavior
- Rewrite plugin and engine e2e tests to align with the new runtime flow and regenerate dist artifacts
- Update Hermes runtime README and package metadata to document pi-ai execution expectations

plugins/fusion-plugin-hermes-runtime/dist/runtime-adapter.d.ts

@@ -1,9 +1,11 @@
-import type { AgentRuntime, AgentRuntimeOptions, AgentSession, AgentSessionResult } from "./types.js";
+import type { AgentRuntime, AgentRuntimeOptions, AgentSession, AgentSessionResult, HermesModelConfig } from "./types.js";
 export declare class HermesRuntimeAdapter implements AgentRuntime {
+    private readonly config;
     readonly id = "hermes";
     readonly name = "Hermes Runtime";
+    constructor(config?: HermesModelConfig);
     createSession(options: AgentRuntimeOptions): Promise<AgentSessionResult>;
-    promptWithFallback(session: AgentSession, prompt: string, options?: unknown): Promise<void>;
+    promptWithFallback(session: AgentSession, prompt: string, _options?: unknown): Promise<void>;
     describeModel(session: AgentSession): string;
     dispose(session: AgentSession): Promise<void>;
 }