feat(devtime): add dev server startup time metric

[dreyfus92]

adds a dev server startup benchmark for every starter. It copies the tracked files into a temp dir, installs with a frozen lockfile outside the timedregion, runs pnpm dev, and times until the first GET / returns 200. this considers 5 runs as requested.

starters aren't touched. ports live in frameworks.json as devServerPort.

things I hit while toying with this:

• astro spawns its dev server detached when it thinks an ai agent is running it, so the kill walks the whole process tree and the server gets a clean env instead of inheriting the terminal's.
• mastro only serves dev routes when the Host header says localhost, which fetch() won't let you set, so the readiness probe uses node:http.
• vite listens on one loopback family depending on what localhost resolves to, so the probe races 127.0.0.1 and ::1.

tables will be populated after this lands and the ci runs 😄

closes: #206

[43081j]

seems good to me but lets wait for @AlexanderKaran to review too