Add LLM OpenAPI schema

[rowan-stein]

User Request

Add OpenAPI schema for the LLM service to expose it through the gateway.

Specification

Create openapi/llm/v1/ directory with REST API schemas for all 12 LLM service operations:

Endpoints

• Providers: POST/GET /providers, GET/PATCH/DELETE /providers/{id}
• Models: POST/GET /models, GET/PATCH/DELETE /models/{id}
• Proxy: POST /responses (opaque body passthrough, supports SSE streaming)

File Structure

openapi/llm/v1/
├── openapi.yaml
├── paths/
│   ├── providers.yaml
│   ├── provider-by-id.yaml
│   ├── models.yaml
│   ├── model-by-id.yaml
│   └── responses.yaml
└── components/
    ├── parameters/
    │   └── IdPath.yaml
    ├── responses/
    │   └── ProblemResponse.yaml
    └── schemas/
        ├── Problem.yaml
        ├── EntityMeta.yaml
        ├── AuthMethod.yaml
        ├── LLMProvider.yaml
        ├── LLMProviderCreateRequest.yaml
        ├── LLMProviderUpdateRequest.yaml
        ├── PaginatedLLMProviders.yaml
        ├── Model.yaml
        ├── ModelCreateRequest.yaml
        ├── ModelUpdateRequest.yaml
        └── PaginatedModels.yaml

Patterns

• Follow existing openapi/files/v1/ and openapi/team/v1/ patterns
• OpenAPI 3.0.3 with $ref for components
• RFC 7807 Problem responses for errors
• Pagination: offset-based (page/perPage/total) matching team API convention
• Proxy endpoint: opaque JSON body with SSE streaming support via text/event-stream

CI

Update .github/workflows/openapi-publish.yml to bundle, lint, and publish the LLM spec.

Schema Details

See the proto at proto/agynio/api/llm/v1/llm.proto for field definitions. Key schemas:

• LLMProvider: EntityMeta + endpoint (uri) + authMethod (enum: bearer)
• Model: EntityMeta + name + llmProviderId (uuid) + remoteName
• EntityMeta: id (uuid) + createdAt (date-time) + updatedAt (date-time, optional)