Add changelog for 2025-06-16 (#519)

Author: quantstruct-bot

fern/changelog/2025-06-14.mdx

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+# Access to `chat` Object in Server Messages
+
+1. **Access to `chat` Object in Server Messages**: You can now access the `chat` object within various server messages, providing additional context about the conversation.

fern/changelog/2025-06-15.mdx

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+# New Storage Credentials Providers
+
+1. **New Storage Provider Credentials Added**: You can now use new credential types [`S3Credential`](https://api.vapi.ai/api#:~:text=S3Credential), [`GcpCredential`](https://api.vapi.ai/api#:~:text=GcpCredential), [`AzureCredential`](https://api.vapi.ai/api#:~:text=AzureCredential), [`SupabaseCredential`](https://api.vapi.ai/api#:~:text=SupabaseCredential), and [`CloudflareCredential`](https://api.vapi.ai/api#:~:text=CloudflareCredential) to integrate with various storage services. This expands your options for storing data seamlessly across different providers.

fern/changelog/2025-06-16.mdx

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+# New Model Selection, Enhanced Edge Conditions, Simplified Credentials, and More
+
+1. **New Model Selection in Workflows**: You can now specify the AI model used in workflows by setting the `model` property in workflow schemas. This allows choosing between OpenAI, Anthropic, Google, or custom models to better suit application requirements.
+
+2. **Enhanced Workflow Edge Conditions**: Workflows now support [`Logic Edge Conditions`](https://api.vapi.ai/api#:~:text=LogicEdgeCondition) and [`Failed Edge Conditions`](https://api.vapi.ai/api#:~:text=FailedEdgeCondition) for edges. Specify logic edge conditions with [Liquid JS templates](https://liquidjs.com/) to enable more complex logic and error handling within workflows, allowing for dynamic and responsive workflow designs.
+
+3. **Simplified Credential Configuration**: Your uploaded credentials are now automatically configured with the correct fallback index, simplifying the setup process with cloud providers.
+
+4. **Updated End Reasons for ElevenLabs**: The following `endedReason` values been removed from `Call`:
+   - `pipeline-error-eleven-labs-503-server-error`
+   - `call.in-progress.error-providerfault-eleven-labs-503-server-error`
+
+   You should update your error handling code to reflect the current set of possible end reasons.
+
+<Warning>
+**Prompt Length Limitations**: The `globalPrompt` in workflows now has a maximum length of 5000 characters, and the `liquid` property in `LogicEdgeCondition` now has a maximum length of 1000 characters. Ensure prompts and conditions stay within these limits to prevent errors.
+</Warning>