docs(readme): refresh pinned versions in the header

Match the versions table and core-stack line to package.json after the
dependency bump: pnpm 12.11.2, Next.js 16.4.1, React 19.3.1,
Drizzle ORM 0.45.4, Zod 4.6.7, Vitest 5.0.4, Playwright 1.64.1.

README.md

@@ -11,14 +11,14 @@ Features a premium animated homepage (typewriter hero, floating orbs, scroll cou
 | Component       | Version        | Notes                                    |
 | --------------- | -------------- | ---------------------------------------- |
 | Node.js         | 26.10.0        | Pinned in `.nvmrc` (`>=26.10.0 <27`)     |
-| pnpm            | 12.10.1        | Pinned via `packageManager`              |
+| pnpm            | 12.11.2        | Pinned via `packageManager`              |
 | npm             | >= 11.x        | Supported alternative                    |
 | yarn            | >= 4.x         | Supported alternative                    |
 | MySQL / MariaDB | 8.0+ / 10.6+   | Shared with the emulator                 |
 | Docker          | 24+            | Optional — for containerized deployment  |
 | Valkey          | 8.x+           | Optional — caching, rate limiting, SSE   |
 
-Core stack: **Next.js 16.4.0** (App Router) · **React 19.3.0** · **TypeScript 7.0.2** · **Drizzle ORM 0.45.3** · **Zod 4.6.5** · **Vitest 5.0.3** · **Biome 2.5.15** · **Playwright 1.63.0**.
+Core stack: **Next.js 16.4.1** (App Router) · **React 19.3.1** · **TypeScript 7.0.2** · **Drizzle ORM 0.45.4** · **Zod 4.6.7** · **Vitest 5.0.4** · **Biome 2.5.15** · **Playwright 1.64.1**.
 
 > Builds must run through the `pnpm` scripts. This host has no swap and
 > `vm.overcommit_memory=0`, so an uncapped `next build` gets OOM-killed by the