fix: generate .d.cts for CJS exports in dual-format packages

[Copilot]

Packages with "type": "module" emit .d.ts (interpreted as ESM) but no .d.cts for CJS consumers, triggering publint warnings.

Build configs

• Added dts: { build: false, autoExtension: true } to cjsConfig in scripts/rslib.base.config.ts — rslib now emits .d.cts alongside .d.ts
• Applied the same to custom CJS lib entries in packages/core/rslib.config.ts and packages/types/rslib.config.ts

Package exports

Split flat types condition into nested import/require across all 8 dual-format packages (cli, core, graph, rspack-plugin, sdk, types, utils, webpack-plugin):

// before
".": {
  "types": "./dist/index.d.ts",
  "import": "./dist/index.js",
  "default": "./dist/index.cjs"
}

// after
".": {
  "import": { "types": "./dist/index.d.ts", "default": "./dist/index.js" },
  "require": { "types": "./dist/index.d.cts", "default": "./dist/index.cjs" }
}