feat: add getting started prompt

packages/llm/src/prompts/getting-started.ts

@@ -0,0 +1,43 @@
+import type { LLMMessage, CodeStructure } from "@codeboard/shared";
+
+export function buildGettingStartedPrompt(
+  structure: CodeStructure,
+  architectureOverview: string,
+  readmeContent?: string,
+  packageJsonContent?: string
+): LLMMessage[] {
+  return [
+    {
+      role: "system",
+      content: `You are writing an onboarding guide for a new developer joining this project. Be specific and actionable.
+
+Output format:
+## Prerequisites
+[list required tools, runtimes, and their versions]
+
+## Setup Steps
+[numbered list of concrete commands and actions to get the project running locally]
+
+## Your First Task
+[suggest a good first contribution — something small but meaningful that touches multiple parts of codebase]`,
+    },
+    {
+      role: "user",
+      content: `Create an onboarding guide for this project.
+
+ARCHITECTURE OVERVIEW:
+${architectureOverview}
+
+${readmeContent ? `README:\n${readmeContent.slice(0, 3000)}` : "README: not available"}
+
+${packageJsonContent ? `PACKAGE.JSON:\n${packageJsonContent.slice(0, 2000)}` : ""}
+
+LANGUAGES: ${[...new Set(structure.files.map((f) => f.language))].join(", ")}
+ENTRY POINTS: ${structure.entryPoints.join(", ") || "none detected"}
+TOTAL FILES: ${structure.files.length}
+TOTAL MODULES: ${structure.modules.length}
+
+Write a concrete, actionable onboarding guide.`,
+    },
+  ];
+}