feat: render config detail inline for alias URLs without redirect

When a browser visits an alias URL like /fullstackjam, render the
config detail page directly instead of redirecting to /username/slug.
This keeps the short URL in the browser address bar.

- Extract ConfigDetail into shared component
- Pass alias resolution via event.locals from hooks
- [username] route conditionally renders config detail or profile

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: fullstackjam

src/app.d.ts

@@ -1,5 +1,11 @@
 declare global {
 	namespace App {
+		interface Locals {
+			aliasConfig?: {
+				username: string;
+				slug: string;
+			};
+		}
 		interface Platform {
 			env: {
 				DB: D1Database;

src/hooks.server.ts

@@ -77,8 +77,7 @@ export const handle: Handle = async ({ event, resolve }) => {
 						}
 					}));
 				} else if (isBrowser) {
-					const baseUrl = env.APP_URL || event.url.origin;
-					return withSecurityHeaders(Response.redirect(`${baseUrl}/${config.username}/${config.slug}`, 302));
+					event.locals.aliasConfig = { username: config.username, slug: config.slug };
 				}
 			}
 		}