feat: populate dnslookup timing with actual DNS resolution time

[Copilot]

The dnslookup field in the Timing object was defined and initialized to 0 but never populated, making it impossible to distinguish DNS resolution time from overall connection time.

Changes

• src/symbols.ts: Add kSocketDnsLookupTime symbol for storing DNS resolution timestamp on sockets
• src/diagnosticsChannel.ts: Capture DNS lookup completion time via Socket.prototype.emit hook on the 'lookup' event (same pattern as the existing Socket.prototype.destroy hook). Compute dnslookup timing relative to request start in the undici:client:sendHeaders handler for first-request-on-socket
• test/options.timing.test.ts: Assert dnslookup > 0 and dnslookup <= connected on first request; assert dnslookup === 0 on reused socket

Result

{
  "queuing": 2.781,
  "dnslookup": 9.038,
  "connected": 12.655,
  "requestHeadersSent": 13.389,
  "requestSent": 13.571,
  "waiting": 24.036,
  "contentDownload": 25.092
}

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• http://registry.npmjs.org:80/urllib/latest
  • Triggering command: /opt/hostedtoolcache/node/24.14.1/x64/bin/node /opt/hostedtoolcache/node/24.14.1/x64/bin/node --experimental-import-meta-resolve --require /home/REDACTED/work/urllib/urllib/node_modules/.pnpm/@voidzero-dev+vite-plus-test@0.1.15_@arethetypeswrong+core@0.18.2_@types+node@22.19.15__7c6ae394869a5d43fd0cf7dc1d33dc1c/node_modules/@voidzero-dev/vite-plus-test/suppress-warnings.cjs --conditions node --conditions development /home/REDACTED/work/urllib/urllib/node_modules/.pnpm/@voidzero-dev+vite-plus-test@0.1.15_@arethetypeswrong+core@0.18.2_@types+node@22.19.15__7c6ae394869a5d43fd0cf7dc1d33dc1c/node_modules/@voidzero-dev/vite-plus-test/dist/workers/forks.js (http block)
  • Triggering command: /opt/hostedtoolcache/node/24.14.1/x64/bin/node /opt/hostedtoolcache/node/24.14.1/x64/bin/node --experimental-import-meta-resolve --require /home/REDACTED/work/urllib/urllib/node_modules/.pnpm/@voidzero-dev+vite-plus-test@0.1.15_@arethetypeswrong+core@0.18.2_@types+node@22.19.15__7c6ae394869a5d43fd0cf7dc1d33dc1c/node_modules/@voidzero-dev/vite-plus-test/suppress-warnings.cjs --conditions node --conditions development /home/REDACTED/work/urllib/urllib/node_modules/.pnpm/@voidzero-dev+vite-plus-test@0.1.15_@arethetypeswrong+core@0.18.2_@types+node@22.19.15__7c6ae394869a5d43fd0cf7dc1d33dc1c/node_modules/@voidzero-dev/vite-plus-test/dist/workers/forks.js k 3899 on REDACTED-w (http block)
• registry.npmmirror.com
  • Triggering command: /opt/hostedtoolcache/node/24.14.1/x64/bin/node /opt/hostedtoolcache/node/24.14.1/x64/bin/node --experimental-import-meta-resolve --require /home/REDACTED/work/urllib/urllib/node_modules/.pnpm/@voidzero-dev+vite-plus-test@0.1.15_@arethetypeswrong+core@0.18.2_@types+node@22.19.15__7c6ae394869a5d43fd0cf7dc1d33dc1c/node_modules/@voidzero-dev/vite-plus-test/suppress-warnings.cjs --conditions node --conditions development /home/REDACTED/work/urllib/urllib/node_modules/.pnpm/@voidzero-dev+vite-plus-test@0.1.15_@arethetypeswrong+core@0.18.2_@types+node@22.19.15__7c6ae394869a5d43fd0cf7dc1d33dc1c/node_modules/@voidzero-dev/vite-plus-test/dist/workers/forks.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)