chore: remove unmaintained legacy LLM providers

Breaking Changes:
- Remove Cloudflare Workers AI provider
- Remove Cohere provider
- Remove Ernie (Baidu) provider
- Remove Llamafile provider
- Remove Local provider
- Remove Maritaca provider
- Remove Watsonx (IBM) provider
- Remove compliance testing suite

This removes dead code that was no longer maintained, tested, or actively used. Users should migrate to actively supported providers like OpenAI, Anthropic, Google AI, Bedrock, or Ollama for local deployments.

Documentation:
- Remove provider integration pages
- Update parity matrix
- Update search index
- Remove provider examples

Author: asdek

CONTRIBUTING.md

@@ -214,9 +214,8 @@ When adding a new LLM provider:
 2. Implement the `llms.Model` interface
 3. Create an internal client package for HTTP interactions
 4. Use `httputil.DefaultClient` for HTTP requests
-5. Add compliance tests: `compliance.NewSuite("yourprovider", model).Run(t)`
-6. Add tests with httprr recordings for HTTP calls
-7. Follow the existing provider patterns for options and error handling
+5. Add tests with httprr recordings for HTTP calls
+6. Follow the existing provider patterns for options and error handling
 
 ##### Adding a New Vector Store
 

doc.go

@@ -90,7 +90,6 @@
 //   - Anthropic (Claude family)
 //   - Google AI (Gemini, PaLM)
 //   - AWS Bedrock (Claude, Llama, Titan)
-//   - Cohere
 //   - Mistral AI
 //   - Ollama (local models)
 //   - Hugging Face Inference

docs/docs/modules/model_io/models/llms/Integrations/llamafile.mdx

@@ -214,16 +214,10 @@ These are newer features from LangChain Python that represent the current direct
 | Google Vertex AI                   | ✅     |
 | AWS Bedrock                        | ✅     |
 | Mistral AI                         | ✅     |
-| Cohere                             | ✅     |
 | Hugging Face                       | ✅     |
 | Ollama                             | ✅     |
-| LlamaFile                          | ✅     |
 | Local LLM                          | ✅     |
 | Groq                               | ✅     |
-| WatsonX                            | ✅     |
-| Ernie (Baidu)                      | ✅     |
-| Cloudflare Workers AI              | ✅     |
-| Maritaca AI                        | ✅     |
 | NVIDIA                             | ✅     |
 | Perplexity                         | ✅     |
 | DeepSeek                           | ✅     |
@@ -241,7 +235,6 @@ These are newer features from LangChain Python that represent the current direct
 | Jina AI                            | ✅     |
 | VoyageAI                           | ✅     |
 | Mistral                            | ✅     |
-| Cohere                             | ❌     |
 | Azure OpenAI                       | ❌     |
 
 ## Tools