infra(04-00): route /c/ → /client/, Dockerfile, Gitea deploy

- Rename src/app/c/[token] → src/app/client/[token]
- Update proxy.ts, ClientRow, admin client detail with /client/ path
- Add output: "standalone" to next.config.ts for Docker build
- Add Dockerfile (multi-stage, node:20-alpine) and .dockerignore
- Push schema to Coolify Postgres via SSH tunnel (drizzle-kit push ✓)
- Update CLAUDE.md constraint 4 to reflect /client/ route
- Add Phase 4 planning artifacts (04-00, 04-RESEARCH, 04-PATTERNS)

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

src/app/admin/clients/[id]/page.tsx

@@ -43,7 +43,7 @@ export default async function ClientDetailPage({
         </div>
         <div className="flex flex-col items-end gap-2">
           <a
-            href={`/c/${client.token}`}
+            href={`/client/${client.token}`}
             target="_blank"
             rel="noopener noreferrer"
             className="text-xs text-[#1A463C] hover:underline font-mono bg-[#1A463C]/5 px-2 py-1 rounded"

src/components/admin/ClientRow.tsx

@@ -56,12 +56,12 @@ export function ClientRow({ client }: { client: ClientWithPayments }) {
       </td>
       <td className="py-3 px-4">
         <a
-          href={`/c/${client.token}`}
+          href={`/client/${client.token}`}
           target="_blank"
           rel="noopener noreferrer"
           className="text-xs text-[#1A463C] hover:underline font-mono"
         >
-          /c/{client.token.slice(0, 8)}…
+          /client/{client.token.slice(0, 8)}…
         </a>
       </td>
     </tr>

src/proxy.ts

@@ -29,8 +29,8 @@ export async function proxy(request: NextRequest) {
   }
 
   // ── CLIENT TOKEN GUARD ───────────────────────────────────────────────────
-  if (pathname.startsWith("/c/")) {
-    const tokenMatch = pathname.match(/^\/c\/([a-zA-Z0-9_-]+)/);
+  if (pathname.startsWith("/client/")) {
+    const tokenMatch = pathname.match(/^\/client\/([a-zA-Z0-9_-]+)/);
     if (!tokenMatch) {
       return NextResponse.rewrite(new URL("/not-found", request.url));
     }
@@ -60,5 +60,5 @@ export async function proxy(request: NextRequest) {
 }
 
 export const config = {
-  matcher: ["/admin/:path*", "/c/:path*"],
+  matcher: ["/admin/:path*", "/client/:path*"],
 };