P0-2: AWS Bedrock provider (chat + embeddings + image)

Problem

LiteLLM ships native AWS Bedrock support (chat / streaming / embeddings / image-gen / Guardrails). ai-gateway has zero — no aisix-provider-bedrock crate.

Bedrock is one of the largest enterprise LLM surfaces; missing it is a hard blocker for every AWS-native customer pitch.

Scope

DP (moonming/ai-gateway)

• New crate crates/aisix-provider-bedrock/ implementing the Bridge trait.
• AWS SigV4 signing (use aws-sigv4 + aws-credential-types).
• Endpoints: POST /model/{modelId}/invoke (sync) + /invoke-with-response-stream (SSE).
• Translate OpenAI-shape chat-completions ↔ Bedrock Converse API.
• Per-model adapter for the Bedrock model families that have non-Converse formats (Anthropic-on-Bedrock / Llama / Titan / Cohere / Stability / Mistral) — start with Anthropic-on-Bedrock since the request shape is closest.
• Embeddings: Titan Embed v1/v2 + Cohere Embed.
• Image: Stability SD3 + Titan Image.

CP (api7/api7ee-3-control-plane)

• Provider enum extended in ai_model.provider (currently openai/anthropic/gemini/deepseek/mock); add bedrock.
• Credential schema must support AWS access key + secret + region + session token (vs OpenAI's single api_key). Tied to #2625 credential resource being org-scoped.

Dashboard UI (api7/AISIX-Cloud)

• Provider picker adds Bedrock.
• Credential form: AWS access key / secret / region (+ optional session token / role ARN for cross-account).
• Model form: Bedrock modelId picker (preload common ones from model_prices_and_context_window.json-equivalent).

e2e

• Mock Bedrock with localstack or a SigV4-aware mock; assert the SigV4 signature + the request body format on the wire.

Estimate

DP 5-7d, CP 2d, UI 1.5d, e2e 1.5d

Start with the proposed crates/aisix-provider-bedrock/ and its Bridge trait, then review the Bedrock invoke and streaming endpoints and the AWS SigV4 requirements. Track the related control-plane provider enum and credential schema, Dashboard provider and credential forms, and the e2e localstack or SigV4-aware mock. Done means chat, streaming, embeddings, image generation, provider configuration, UI support, and wire-level signature and body assertions are covered.