feat: initialize warpbox.dev project structure and backend

Initialize the repository with the core Go backend architecture and a frontend mockup for warpbox.dev, a self-hosted file-sharing application.

- Set up Go backend modules for configuration, HTTP server, middleware, handlers, and templates.
- Add local development scripts, environment templates, and basic project configuration.
- Include a React-based frontend mockup under the docs directory.

docs/Mock-Up/Mockup Magic/src/routes/admin.settings.tsx

@@ -0,0 +1,73 @@
+import { createFileRoute } from "@tanstack/react-router";
+import { AppShell } from "@/components/layout/AppShell";
+import { Card, CardContent } from "@/components/ui/card";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { Switch } from "@/components/ui/switch";
+import { Separator } from "@/components/ui/separator";
+
+export const Route = createFileRoute("/admin/settings")({
+  head: () => ({ meta: [{ title: "Admin · Settings — warpbox.dev" }] }),
+  component: AdminSettings,
+});
+
+function AdminSettings() {
+  return (
+    <AppShell variant="admin" title="Admin · Settings">
+      <div className="mx-auto max-w-2xl space-y-6">
+        <Card>
+          <CardContent className="p-6">
+            <h2 className="font-medium">Instance branding</h2>
+            <div className="mt-4 grid gap-4 sm:grid-cols-2">
+              <div className="space-y-1.5"><Label>Instance name</Label><Input defaultValue="warpbox.dev" /></div>
+              <div className="space-y-1.5"><Label>Tagline</Label><Input defaultValue="Send a file. Get a link." /></div>
+              <div className="space-y-1.5"><Label>Primary color</Label><Input defaultValue="#3b82f6" /></div>
+              <div className="space-y-1.5"><Label>Logo URL</Label><Input placeholder="https://…" /></div>
+            </div>
+          </CardContent>
+        </Card>
+
+        <Card>
+          <CardContent className="p-6">
+            <h2 className="font-medium">Limits & retention</h2>
+            <div className="mt-4 grid gap-4 sm:grid-cols-2">
+              <div className="space-y-1.5"><Label>Max file size (MB)</Label><Input type="number" defaultValue={5120} /></div>
+              <div className="space-y-1.5"><Label>Default expiry (days)</Label><Input type="number" defaultValue={7} /></div>
+              <div className="space-y-1.5"><Label>Anonymous quota / IP (MB/day)</Label><Input type="number" defaultValue={2048} /></div>
+              <div className="space-y-1.5"><Label>Per-user quota (GB)</Label><Input type="number" defaultValue={50} /></div>
+            </div>
+            <Separator className="my-5" />
+            <div className="space-y-3">
+              {[
+                ["Allow anonymous uploads", true],
+                ["Allow registrations", true],
+                ["Require password on public links", false],
+                ["Show 'Powered by warpbox' footer", true],
+              ].map(([label, on]) => (
+                <div key={label as string} className="flex items-center justify-between">
+                  <span className="text-sm">{label as string}</span>
+                  <Switch defaultChecked={on as boolean} />
+                </div>
+              ))}
+            </div>
+            <div className="mt-5"><Button>Save settings</Button></div>
+          </CardContent>
+        </Card>
+
+        <Card>
+          <CardContent className="p-6">
+            <h2 className="font-medium">SMTP</h2>
+            <div className="mt-4 grid gap-4 sm:grid-cols-2">
+              <div className="space-y-1.5"><Label>Host</Label><Input defaultValue="smtp.example.com" /></div>
+              <div className="space-y-1.5"><Label>Port</Label><Input defaultValue={587} /></div>
+              <div className="space-y-1.5"><Label>Username</Label><Input defaultValue="warpbox" /></div>
+              <div className="space-y-1.5"><Label>Password</Label><Input type="password" /></div>
+            </div>
+            <div className="mt-4 flex gap-2"><Button>Save</Button><Button variant="outline">Send test email</Button></div>
+          </CardContent>
+        </Card>
+      </div>
+    </AppShell>
+  );
+}