feat: initial CodeBoard monorepo scaffold

Turborepo monorepo with npm workspaces:
- apps/web: Next.js 14 frontend with Tailwind v4, SSE progress, doc viewer
- apps/worker: BullMQ job processor (clone → parse → LLM generate)
- packages/shared: TypeScript types
- packages/parser: Babel-based AST parser (JS/TS) + regex (Python)
- packages/llm: OpenAI/Anthropic provider abstraction + prompt pipeline
- packages/diagrams: Mermaid architecture & dependency graph generators
- packages/database: Prisma schema (PostgreSQL)
- Docker multi-stage build (web + worker targets)

All packages compile successfully with tsc and next build.

apps/web/src/components/navbar.tsx

@@ -0,0 +1,94 @@
+"use client";
+
+import { useState } from "react";
+import Link from "next/link";
+import { Code2, Menu, X, Github } from "lucide-react";
+
+export function Navbar() {
+  const [isOpen, setIsOpen] = useState(false);
+
+  const navLinks = [
+    { href: "/#how-it-works", label: "How it Works" },
+    { href: "/#features", label: "Features" },
+  ];
+
+  return (
+    <header className="fixed top-0 left-0 right-0 z-50">
+      <nav className="glass border-b border-white/5">
+        <div className="max-w-6xl mx-auto px-4 sm:px-6 lg:px-8">
+          <div className="flex items-center justify-between h-16">
+            <Link href="/" className="flex items-center gap-2 group">
+              <div className="w-8 h-8 rounded-lg bg-gradient-to-br from-blue-500 to-purple-600 flex items-center justify-center group-hover:shadow-lg group-hover:shadow-blue-500/25 transition-shadow">
+                <Code2 className="w-5 h-5 text-white" />
+              </div>
+              <span className="text-lg font-semibold text-white">
+                CodeBoard
+              </span>
+            </Link>
+
+            <div className="hidden md:flex items-center gap-8">
+              {navLinks.map((link) => (
+                <Link
+                  key={link.href}
+                  href={link.href}
+                  className="text-sm text-zinc-400 hover:text-white transition-colors"
+                >
+                  {link.label}
+                </Link>
+              ))}
+              
+              <a
+                href="https://github.com"
+                target="_blank"
+                rel="noopener noreferrer"
+                className="flex items-center gap-2 text-sm text-zinc-400 hover:text-white transition-colors"
+              >
+                <Github className="w-4 h-4" />
+                GitHub
+              </a>
+            </div>
+
+            <button
+              onClick={() => setIsOpen(!isOpen)}
+              className="md:hidden p-2 text-zinc-400 hover:text-white"
+              aria-label="Toggle menu"
+            >
+              {isOpen ? (
+                <X className="w-6 h-6" />
+              ) : (
+                <Menu className="w-6 h-6" />
+              )}
+            </button>
+          </div>
+        </div>
+
+        {isOpen && (
+          <div className="md:hidden border-t border-white/5 bg-black/50 backdrop-blur-xl">
+            <div className="px-4 py-4 space-y-3">
+              {navLinks.map((link) => (
+                <Link
+                  key={link.href}
+                  href={link.href}
+                  onClick={() => setIsOpen(false)}
+                  className="block text-sm text-zinc-400 hover:text-white transition-colors py-2"
+                >
+                  {link.label}
+                </Link>
+              ))}
+              
+              <a
+                href="https://github.com"
+                target="_blank"
+                rel="noopener noreferrer"
+                className="flex items-center gap-2 text-sm text-zinc-400 hover:text-white transition-colors py-2"
+              >
+                <Github className="w-4 h-4" />
+                GitHub
+              </a>
+            </div>
+          </div>
+        )}
+      </nav>
+    </header>
+  );
+}