feat(FN-3195): document llama.cpp provider setup and onboarding

Docs(FN-3195): adds llama.cpp provider setup and onboarding documentation to the main and dashboard READMEs.

Fusion-Task-Id: FN-3195

packages/cli/src/commands/__tests__/llama-cpp-extension.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, it } from "vitest";
+import {
+  resolveLlamaCppExtension,
+  resolveLlamaCppExtensionPaths,
+} from "../llama-cpp-extension.js";
+
+describe("resolveLlamaCppExtension", () => {
+  it("finds the bundled @fusion/pi-llama-cpp package", () => {
+    const result = resolveLlamaCppExtension();
+    expect(result.status).toBe("ok");
+    if (result.status === "ok") {
+      expect(result.path).toMatch(/pi-llama-cpp[\\/]index\.ts$/);
+      expect(result.packageVersion).toMatch(/^\d+\.\d+\.\d+$/);
+    }
+  });
+});
+
+describe("resolveLlamaCppExtensionPaths", () => {
+  it("returns empty when useLlamaCpp is off", () => {
+    const result = resolveLlamaCppExtensionPaths({});
+    expect(result.paths).toEqual([]);
+    expect(result.warning).toBeUndefined();
+    expect(result.resolution).toBeNull();
+  });
+
+  it("returns extension path when useLlamaCpp is on", () => {
+    const result = resolveLlamaCppExtensionPaths({ useLlamaCpp: true });
+    expect(result.paths).toHaveLength(1);
+    expect(result.paths[0]).toMatch(/pi-llama-cpp[\\/]index\.ts$/);
+    expect(result.resolution?.status).toBe("ok");
+  });
+});
+
+describe("cached resolution roundtrip", () => {
+  it("set/get preserves snapshot", async () => {
+    const { setCachedLlamaCppResolution, getCachedLlamaCppResolution } =
+      await import("../llama-cpp-extension.js");
+    setCachedLlamaCppResolution({ status: "not-installed" });
+    expect(getCachedLlamaCppResolution()).toEqual({ status: "not-installed" });
+    setCachedLlamaCppResolution(null);
+    expect(getCachedLlamaCppResolution()).toBeNull();
+  });
+});