refactor(executor): split providers and preserve legacy entrypoints

feat: passthrough upstream response headers to clients

refactor(translator, executor): remove redundant `bytes.Clone` calls for improved performance

refactor(executor): optimize payload cloning and streamline SDK translator usage

fix(executor): handle "global" location in AI platform URL generation

feat(openai): add responses/compact support

feat(executor): add request_id to error logs

feat(executor): apply payload rules using requested model

feat(registry): support provider-specific model info lookup

feat(vertex): add Imagen image generation model support

refactor(thinking): pass source and target formats to ApplyThinking for cross-format validation

fix(executor): properly handle thinking application errors

refactor: improve thinking logic

feat(executor): add HttpRequest support across executors for better http request handling

feat(executor): enhance payload translation with original request context

refactor(executor): resolve upstream model at conductor level before execution

fix(executor): use upstream model for thinking config and payload translation

refactor(executor): relocate gemini token counters

refactor(executor): clarify executor comments and oauth names

refactor(executor): clarify providers and streams

Merge pull request #481 from sususu98/fix/increase-buffer-size

feat(util): implement dynamic thinking suffix normalization and refactor budget resolution logic

fix(executor): increase buffer size for stream scanners to 50MB across multiple executors

fix(executor): centralize default thinking config

feat(executor): normalize thinking budget across all Gemini executors

**refactor(cliproxy, config): remove vertex-compat flow, streamline Vertex API key handling**

feat: Add support for VertexAI compatible service (#375)

**fix(runtime): simplify scanner buffer allocation in executor implementations**

**feat(runtime): add payload configuration support for executors**

feat(vertex, management): enhance token handling and OAuth2 integration

feat(vertex): add support for Vertex AI Gemini authentication and execution