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/pi-module.d.ts

@@ -1,29 +1,14 @@
-export interface PiAgentSession {
-    dispose?: () => Promise<void> | void;
-}
-export interface PiAgentResult {
-    session: PiAgentSession;
-    sessionFile?: string;
-}
-export interface PiAgentOptions {
-    cwd: string;
+import { type Message } from "@mariozechner/pi-ai";
+import type { HermesCallbacks, HermesStreamSession, ResolvedModelConfig } from "./types.js";
+export declare function resolveModelConfig(settings?: Record<string, unknown>): ResolvedModelConfig;
+export declare function createStreamSession(options: {
+    provider: string;
+    modelId: string;
+    apiKey?: string;
+    thinkingLevel?: string;
     systemPrompt: string;
-    tools?: "coding" | "readonly";
-    customTools?: unknown;
-    onText?: (text: string) => void;
-    onThinking?: (text: string) => void;
-    onToolStart?: (toolName: string, args?: Record<string, unknown>) => void;
-    onToolEnd?: (toolName: string, isError: boolean, result?: unknown) => void;
-    defaultProvider?: string;
-    defaultModelId?: string;
-    fallbackProvider?: string;
-    fallbackModelId?: string;
-    defaultThinkingLevel?: string;
-    sessionManager?: unknown;
-    skillSelection?: unknown;
-    skills?: string[];
-}
-export declare const createFnAgent: (options: PiAgentOptions) => Promise<PiAgentResult>;
-export declare const promptWithFallback: (session: PiAgentSession, prompt: string, options?: unknown) => Promise<void>;
-export declare const describeModel: (session: PiAgentSession) => string;
+    callbacks?: HermesCallbacks;
+}): HermesStreamSession;
+export declare function streamPrompt(session: HermesStreamSession, _userMessage: Message): Promise<void>;
+export declare function describeStreamModel(session: HermesStreamSession): string;
 //# sourceMappingURL=pi-module.d.ts.map