CI checks

To be more sure we're giving people working code to base their applications on, this PR adds a github workflow that run the following on CI for each starter:

• ts typechecks
• pnpm dev and check that cURL-ing it comes back with a 200
• pnpm preview (which also does pnpm build) and check that cURL-ing it comes back with a 200

New package.json scripts in starters

• pnpm check: runs tsc (users can change it to do other checks too if desired)
• pnpm preview: builds then run vite preview

No more port setting

We no longer set a port (2332) for the dev server - this was a remnant of where we started when building the sdk that we don't need anymore. This means vite dev will now use its own default port (5173), and that users can do pnpm dev --port <PORT> to override this.

dev:init is now db agnostic

As long as a project has migrate:dev and seed scripts in their package.json, we'll run them on postinstall (previously we only ran them if we found a prisma schema). This means the drizzle starter also only needs pnpm i && pnpm dev to get a running server