feat: documentation pages and updated model pricing

- Add 13 documentation pages under /docs (getting-started, concepts, SDK refs, integrations, API reference, self-hosting, OpenCode plugin)
- Shared docs layout with collapsible sidebar navigation
- Update model pricing across all SDKs: add GPT-5.x, GPT-4.1, o3/o4-mini, Claude 4.5 series, claude-opus-4-6
- Update trace-analytics context window lookup with current models

apps/web/src/app/docs/docs-sidebar.tsx

@@ -0,0 +1,121 @@
+"use client";
+
+import { useState } from "react";
+
+interface NavItem {
+  title: string;
+  href: string;
+}
+
+interface NavSection {
+  heading: string;
+  items: NavItem[];
+}
+
+const navigation: NavSection[] = [
+  {
+    heading: "Overview",
+    items: [
+      { title: "Introduction", href: "/docs" },
+      { title: "Getting Started", href: "/docs/getting-started" },
+      { title: "Core Concepts", href: "/docs/concepts" },
+    ],
+  },
+  {
+    heading: "SDKs",
+    items: [
+      { title: "Python SDK", href: "/docs/python-sdk" },
+      { title: "TypeScript SDK", href: "/docs/typescript-sdk" },
+    ],
+  },
+  {
+    heading: "Integrations",
+    items: [
+      { title: "OpenAI", href: "/docs/integrations/openai" },
+      { title: "Anthropic", href: "/docs/integrations/anthropic" },
+      { title: "LangChain", href: "/docs/integrations/langchain" },
+    ],
+  },
+  {
+    heading: "Tools",
+    items: [{ title: "OpenCode Plugin", href: "/docs/opencode-plugin" }],
+  },
+  {
+    heading: "Reference",
+    items: [
+      { title: "REST API", href: "/docs/api-reference" },
+      { title: "Self-Hosting", href: "/docs/self-hosting" },
+    ],
+  },
+];
+
+function SidebarContent() {
+  return (
+    <nav className="space-y-6">
+      {navigation.map((section) => (
+        <div key={section.heading}>
+          <h4 className="text-xs font-semibold uppercase tracking-wider text-neutral-500 mb-2 px-3">
+            {section.heading}
+          </h4>
+          <ul className="space-y-0.5">
+            {section.items.map((item) => (
+              <li key={item.href}>
+                <a
+                  href={item.href}
+                  className="block px-3 py-1.5 text-sm text-neutral-400 hover:text-neutral-100 hover:bg-neutral-800/50 rounded-md transition-colors"
+                >
+                  {item.title}
+                </a>
+              </li>
+            ))}
+          </ul>
+        </div>
+      ))}
+    </nav>
+  );
+}
+
+export function DocsSidebar() {
+  const [mobileOpen, setMobileOpen] = useState(false);
+
+  return (
+    <>
+      <button
+        type="button"
+        onClick={() => setMobileOpen(!mobileOpen)}
+        className="lg:hidden fixed bottom-4 right-4 z-50 w-12 h-12 rounded-full bg-emerald-500 text-neutral-950 shadow-lg shadow-emerald-500/25 flex items-center justify-center"
+        aria-label="Toggle navigation"
+      >
+        <svg className="w-5 h-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+          {mobileOpen ? (
+            <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
+          ) : (
+            <path strokeLinecap="round" strokeLinejoin="round" d="M4 6h16M4 12h16M4 18h16" />
+          )}
+        </svg>
+      </button>
+
+      {mobileOpen && (
+        <div className="lg:hidden fixed inset-0 z-40">
+          <div
+            className="absolute inset-0 bg-neutral-950/80 backdrop-blur-sm"
+            onClick={() => setMobileOpen(false)}
+            onKeyDown={(e) => {
+              if (e.key === "Escape") setMobileOpen(false);
+            }}
+            role="button"
+            tabIndex={0}
+            aria-label="Close navigation"
+          />
+          <div className="absolute left-0 top-14 bottom-0 w-72 bg-neutral-950 border-r border-neutral-800/50 p-6 overflow-y-auto">
+            <SidebarContent />
+          </div>
+        </div>
+      )}
+
+      <aside className="hidden lg:block w-64 flex-shrink-0 border-r border-neutral-800/50 sticky top-14 h-[calc(100vh-3.5rem)] overflow-y-auto py-8 px-4">
+        <SidebarContent />
+      </aside>
+    </>
+  );
+}