docs: Add comprehensive Files API and Vector Store integration doc (#3279)

docs: Add comprehensive Files API and Vector Store integration
documentation

- Add Files API documentation with OpenAI-compatible endpoints
- Create comprehensive guide for OpenAI-compatible file operations
- Reorganize documentation structure: move file operations to files/
directory
- Add vector store provider documentation for Milvus, SQLite-vec, FAISS
- Clean up redundant files and improve navigation
- Update cross-references and eliminate documentation duplication
- Support for release 0.2.14 FileResponse and Vector Store API features

# What does this PR do?
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relevant issues if applicable. -->

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## Test Plan
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summaries. *Provide clear instructions so the plan can be easily
re-executed.* -->

docs/docs/api-experimental/index.mdx

@@ -0,0 +1,128 @@
+---
+title: Experimental APIs
+description: APIs in development with limited support
+sidebar_label: Experimental
+sidebar_position: 1
+---
+
+# Experimental APIs
+
+This section contains APIs that are currently in development and may have limited support or stability. These APIs are available for testing and feedback but should not be used in production environments.
+
+:::warning Experimental Notice
+These APIs are experimental and may change without notice. Use with caution and provide feedback to help improve them.
+:::
+
+## Current Experimental APIs
+
+### Batch Inference API
+Run inference on a dataset of inputs in batch mode for improved efficiency.
+
+**Status:** In Development
+**Provider Support:** Limited
+**Use Case:** Large-scale inference operations
+
+**Features:**
+- Batch processing of multiple inputs
+- Optimized resource utilization
+- Progress tracking and monitoring
+
+### Batch Agents API
+Run agentic workflows on a dataset of inputs in batch mode.
+
+**Status:** In Development
+**Provider Support:** Limited
+**Use Case:** Large-scale agent operations
+
+**Features:**
+- Batch agent execution
+- Parallel processing capabilities
+- Result aggregation and analysis
+
+### Synthetic Data Generation API
+Generate synthetic data for model development and testing.
+
+**Status:** Early Development
+**Provider Support:** Very Limited
+**Use Case:** Training data augmentation
+
+**Features:**
+- Automated data generation
+- Quality control mechanisms
+- Customizable generation parameters
+
+### Batches API (OpenAI-compatible)
+OpenAI-compatible batch management for inference operations.
+
+**Status:** In Development
+**Provider Support:** Limited
+**Use Case:** OpenAI batch processing compatibility
+
+**Features:**
+- OpenAI batch API compatibility
+- Job scheduling and management
+- Status tracking and monitoring
+
+## Getting Started with Experimental APIs
+
+### Prerequisites
+- Llama Stack server running with experimental features enabled
+- Appropriate provider configurations
+- Understanding of API limitations
+
+### Configuration
+Experimental APIs may require special configuration flags or provider settings. Check the specific API documentation for setup requirements.
+
+### Usage Guidelines
+1. **Testing Only**: Use experimental APIs for testing and development only
+2. **Monitor Changes**: Watch for updates and breaking changes
+3. **Provide Feedback**: Report issues and suggest improvements
+4. **Backup Data**: Always backup important data when using experimental features
+
+## Feedback and Contribution
+
+We encourage feedback on experimental APIs to help improve them:
+
+### Reporting Issues
+- Use GitHub issues with the "experimental" label
+- Include detailed error messages and reproduction steps
+- Specify the API version and provider being used
+
+### Feature Requests
+- Submit feature requests through GitHub discussions
+- Provide use cases and expected behavior
+- Consider contributing implementations
+
+### Testing
+- Test experimental APIs in your environment
+- Report performance issues and optimization opportunities
+- Share success stories and use cases
+
+## Migration to Stable APIs
+
+As experimental APIs mature, they will be moved to the stable API section. When this happens:
+
+1. **Announcement**: We'll announce the promotion in release notes
+2. **Migration Guide**: Detailed migration instructions will be provided
+3. **Deprecation Timeline**: Experimental versions will be deprecated with notice
+4. **Support**: Full support will be available for stable versions
+
+## Provider Support
+
+Experimental APIs may have limited provider support. Check the specific API documentation for:
+
+- Supported providers
+- Configuration requirements
+- Known limitations
+- Performance characteristics
+
+## Roadmap
+
+Experimental APIs are part of our ongoing development roadmap:
+
+- **Q1 2024**: Batch Inference API stabilization
+- **Q2 2024**: Batch Agents API improvements
+- **Q3 2024**: Synthetic Data Generation API expansion
+- **Q4 2024**: Batches API full OpenAI compatibility
+
+For the latest updates, follow our [GitHub releases](https://github.com/llamastack/llama-stack/releases) and [roadmap discussions](https://github.com/llamastack/llama-stack/discussions).