fix(packaging): resolve correct .d.cts types for CJS consumers

Each package shipped a single top-level "types" in its exports map
pointing at the ESM `.d.ts`. Because every package is `"type": "module"`,
TypeScript's node16/nodenext resolution interprets that declaration as
ESM, so CommonJS consumers (moduleResolution node16/nodenext) cannot
import the packages:
  - TS1479 on value imports
  - TS1541 on type-only imports

The matching `.d.cts` declarations are already emitted by tsup but were
never referenced. Nest the `types` condition under each `import`/`require`
branch so CJS consumers resolve `.d.cts` and ESM consumers resolve `.d.ts`.
This is purely additive to type resolution — runtime entries and ESM
consumers are unchanged.

Verified with @arethetypeswrong/cli (all green across node10, node16
from CJS and ESM, and bundler) and against a real CommonJS + node16
consumer build.

Fixes #748

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: david-illing-ck

packages/browser/package.json

@@ -9,9 +9,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {

packages/client/package.json

@@ -9,9 +9,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {

packages/core/package.json

@@ -9,9 +9,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {

packages/langchain/package.json

@@ -9,9 +9,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {

packages/openai/package.json

@@ -9,9 +9,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {

packages/otel/package.json

@@ -19,9 +19,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {

packages/tracing/package.json

@@ -19,9 +19,14 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
     }
   },
   "scripts": {