refactor: use import type for type-only imports across all packages

Add explicit `type` annotations to all type-only imports and exports.
This is a pure TypeScript syntax change with no runtime effect -- the
compiled JavaScript output is identical. It prepares for Node 24's
type stripping, which requires `import type` for type-only imports
since they are erased at runtime.

93 files changed across dev-server, test-runner, rollup-plugin, and
storybook packages.

Assisted-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bennypowers

packages/dev-server-core/src/plugins/Plugin.ts

@@ -1,9 +1,9 @@
 import { FSWatcher } from 'chokidar';
 import Koa, { Context } from 'koa';
-import { Server } from 'net';
+import { type Server } from 'net';
 
-import { DevServerCoreConfig } from '../server/DevServerCoreConfig';
-import { Logger } from '../logger/Logger';
+import type { DevServerCoreConfig } from '../server/DevServerCoreConfig';
+import type { Logger } from '../logger/Logger';
 import { WebSocketsManager } from '../web-sockets/WebSocketsManager';
 
 export type ServeResult =

packages/dev-server-core/src/server/createServer.ts

@@ -6,9 +6,9 @@ import http2Server from 'http2';
 import fs from 'fs';
 import net, { Server, Socket, ListenOptions } from 'net';
 
-import { DevServerCoreConfig } from './DevServerCoreConfig.js';
+import type { DevServerCoreConfig } from './DevServerCoreConfig.js';
 import { createMiddleware } from './createMiddleware.js';
-import { Logger } from '../logger/Logger.js';
+import type { Logger } from '../logger/Logger.js';
 import { addPlugins } from './addPlugins.js';
 
 /**

packages/dev-server-rollup/src/index.ts

@@ -1,4 +1,4 @@
-export { RollupNodeResolveOptions, nodeResolve } from '@rollup/plugin-node-resolve';
+export { type RollupNodeResolveOptions, nodeResolve } from '@rollup/plugin-node-resolve';
 export { fromRollup } from './fromRollup.js';
 export { rollupAdapter } from './rollupAdapter.js';
 export { rollupBundlePlugin } from './rollupBundlePlugin.js';

packages/dev-server/src/config/DevServerConfig.ts

@@ -1,5 +1,5 @@
-import { DevServerCoreConfig } from '@web/dev-server-core';
-import { RollupNodeResolveOptions } from '@web/dev-server-rollup';
+import { type DevServerCoreConfig } from '@web/dev-server-core';
+import { type RollupNodeResolveOptions } from '@web/dev-server-rollup';
 
 export interface DevServerConfig extends DevServerCoreConfig {
   /**

packages/dev-server/src/config/mergeConfigs.ts

@@ -1,4 +1,4 @@
-import { DevServerConfig } from './DevServerConfig.js';
+import { type DevServerConfig } from './DevServerConfig.js';
 
 const arrayKeys = ['plugins', 'middleware'];
 

packages/dev-server/src/config/parseConfig.ts

@@ -1,9 +1,9 @@
 import { getPortPromise } from 'portfinder';
 import path from 'path';
 
-import { DevServerCliArgs } from './readCliArgs.js';
+import { type DevServerCliArgs } from './readCliArgs.js';
 import { mergeConfigs } from './mergeConfigs.js';
-import { DevServerConfig } from './DevServerConfig.js';
+import { type DevServerConfig } from './DevServerConfig.js';
 import { esbuildPlugin } from '../plugins/esbuildPlugin.js';
 import { watchPlugin } from '../plugins/watchPlugin.js';
 import { nodeResolvePlugin } from '../plugins/nodeResolvePlugin.js';

packages/dev-server/src/config/readCliArgs.ts

@@ -1,7 +1,7 @@
 import commandLineArgs from 'command-line-args';
 import commandLineUsage, { OptionDefinition } from 'command-line-usage';
 import camelCase from 'camelcase';
-import { DevServerConfig } from './DevServerConfig.js';
+import { type DevServerConfig } from './DevServerConfig.js';
 
 export interface DevServerCliArgs
   extends Partial<

packages/dev-server/src/logger/DevServerLogger.ts

@@ -1,4 +1,4 @@
-import { Logger, PluginSyntaxError } from '@web/dev-server-core';
+import { type Logger, PluginSyntaxError } from '@web/dev-server-core';
 import { codeFrameColumns } from '@babel/code-frame';
 import path from 'path';
 import { red, cyan } from 'nanocolors';

packages/dev-server/src/logger/createLogger.ts

@@ -1,4 +1,4 @@
-import { Plugin } from '@web/dev-server-core';
+import { type Plugin } from '@web/dev-server-core';
 import { DevServerLogger } from './DevServerLogger.js';
 import { logStartMessage } from './logStartMessage.js';
 

packages/dev-server/src/logger/logStartMessage.ts

@@ -1,5 +1,5 @@
-import { DevServerConfig } from '../config/DevServerConfig';
-import { Logger } from '@web/dev-server-core';
+import { type DevServerConfig } from '../config/DevServerConfig';
+import { type Logger } from '@web/dev-server-core';
 import internalIp from 'internal-ip';
 import { bold, cyan, white } from 'nanocolors';