[P3] Update tsconfig target from ES2017 to ES2022 for Node 24 compatibility

[itsmiso-ai]

Problem: The tsconfig.json sets target: "ES2017", which causes TypeScript to downlevel modern JavaScript syntax (async iteration, optional chaining, nullish coalescing) to ES2017-compatible output. Since the runtime environment is Node.js 24 (per package.json "node": "=24" and the Dockerfile base image node:24-bookworm-slim), this adds unnecessary transpilation overhead and produces larger, slower code. Node 24 natively supports all ES2022+ features.

Evidence:

// tsconfig.json
{
  "compilerOptions": {
    "target": "ES2017",
    // ...
  }
}

# Dockerfile
FROM node:24-bookworm-slim AS base

// package.json
"engines": { "node": "=24" }

Node 24 supports:

• ES2022 features natively (class fields, static initialization blocks, .at(), regex match indices)
• ESNext async iteration, top-level await, and Array.fromAsync (ES2024+)
• The Next.js bundler module resolution already handles the rest

Acceptance:

• tsconfig.json target is changed from "ES2017" to "ES2022" (or "ESNext")
• npm run typecheck passes with no new errors
• npm run build succeeds and produces a working Next.js standalone build
• CI typecheck and build steps pass
• Optional: verify the output .next/ bundle size is smaller than before