chore(release): 2.0.0

Major release: @google/generative-ai → @google/genai migration changes
the type signature of GeminiConfig.safetySettings, which is a breaking
change for consumers using that option.

Other changes accumulated since 1.3.3:
- @anthropic-ai/sdk 0.65 → 0.97
- openai 4 → 6
- @types/node 24 → 25
- TypeScript 6 support (peer widened to ^5 || ^6)
- Default Gemini model: gemini-1.5-flash → gemini-2.5-flash

package.json

@@ -1,6 +1,6 @@
 {
   "name": "simple-ai-provider",
-  "version": "1.3.3",
+  "version": "2.0.0",
   "description": "A simple and extensible AI provider package for easy integration of multiple AI services",
   "main": "dist/index.js",
   "module": "dist/index.mjs",