chore: Remove env option

Merging of envs may need to be done at the module top-level
in consuming apps to be exposed to scripts
like database migrations.
Moreover, the server.env decoration can be overriden.

src/index.ts

@@ -3,19 +3,17 @@ import sensible from '@fastify/sensible'
 import underPressurePlugin, {
   UnderPressureOptions
 } from '@fastify/under-pressure'
-import { createEnv } from '@t3-oss/env-core'
 import Fastify, { FastifyHttpsOptions, FastifyInstance } from 'fastify'
 import https from 'node:https'
-import { ZodType } from 'zod'
-import { fastifyMicroEnv } from './environment'
+import { fastifyMicroEnv, type FastifyMicroEnv } from './environment'
 import gracefulShutdown, { GracefulShutdownOptions } from './graceful-shutdown'
 import { getLoggerOptions, makeReqIdGenerator } from './logger'
 import sentry, { SentryOptions } from './sentry'
 
 declare module 'fastify' {
   interface FastifyInstance {
     name?: string
-    env: ReturnType<typeof fastifyMicroEnv>
+    env: FastifyMicroEnv
   }
 }
 
@@ -27,8 +25,6 @@ export type Options = Omit<FastifyHttpsOptions<https.Server>, 'https'> & {
    */
   name?: string
 
-  env?: Record<string, ZodType>
-
   /**
    * Enable HTTPS for your server by passing a TLS configuration.
    * Disabled by default.
@@ -116,12 +112,7 @@ export function createServer(
     https: null
   }
 ) {
-  const env = createEnv({
-    server: options.env ?? {},
-    extends: [fastifyMicroEnv()],
-    runtimeEnv: process.env,
-    isServer: true
-  })
+  const env = fastifyMicroEnv()
   const server = Fastify({
     logger: getLoggerOptions(options, env),
     genReqId: makeReqIdGenerator(env),