feat(FN-1531): add memory-aware dev entrypoint

- Add scripts/dev-with-memory.mjs entrypoint script
- Configure memory monitoring and optimization for development mode
- Update package.json scripts to include memory-aware dev option

scripts/dev-with-memory.mjs

@@ -0,0 +1,32 @@
+#!/usr/bin/env node
+/**
+ * Memory-aware development entrypoint for Fusion.
+ * 
+ * This script increases the Node.js heap size to prevent memory pressure
+ * during the initial build/start sequence, while preserving argument
+ * pass-through for documented invocations like `pnpm dev dashboard`.
+ * 
+ * Cross-platform: Works on Windows, macOS, and Linux.
+ */
+
+// Set increased heap size (8GB) to prevent OOM during initial build/start
+const MEMORY_MB = process.env.FUSION_DEV_MEMORY_MB || "8192";
+process.env.NODE_OPTIONS = `--max-old-space-size=${MEMORY_MB} ${process.env.NODE_OPTIONS || ""}`.trim();
+
+// Spawn the actual dev command with all arguments passed through
+const { spawn } = await import("child_process");
+const args = process.argv.slice(2);
+
+// If no args, run default: build + CLI
+if (args.length === 0) {
+  const pnpm = spawn("pnpm", ["build"], { stdio: "inherit", shell: true });
+  pnpm.on("close", (code) => {
+    if (code !== 0) process.exit(code ?? 1);
+    const tsx = spawn("pnpm", ["exec", "tsx", "packages/cli/src/bin.ts"], { stdio: "inherit", shell: true });
+    tsx.on("close", (c) => process.exit(c ?? 1));
+  });
+} else {
+  // Forward all arguments (e.g., "dashboard", "task list", etc.)
+  const cmd = spawn("pnpm", ["build", "&&", "tsx", "packages/cli/src/bin.ts", ...args], { stdio: "inherit", shell: true });
+  cmd.on("close", (c) => process.exit(c ?? 1));
+}