feat(ai): support multipart tool results

[arjunkmrm]

Custom tool files currently become JSON strings before reaching provider APIs. Add a shared typed content result and encode files inside native OpenAI and Anthropic results. Compatible chat providers receive labelled attachment messages after the tool-result batch; Bedrock uses native images where supported and the same fallback for other media and text history.

Tool result content
  -> provider adapter
     -> native result content
     -> labelled attachment message when required

packages/ai/
  clavia/src/ToolResult.ts                +75/-0
  clavia/test/ProviderStreams.test.ts    +142/-0
  openai/src/OpenAiLanguageModel.ts       +30/-2
  anthropic/src/AnthropicLanguageModel.ts +35/-2
  openai-compat/src/OpenAiLanguageModel.ts +3/-2
  openrouter/src/OpenRouterLanguageModel.ts +3/-2
  bedrock/src/BedrockLanguageModel.ts     +52/-3
  bedrock/test/ToolContent.test.ts        +89/-0
  six package manifests                 +10/-8
packages/effect/typetest/Schedule.tst.ts   +2/-2
scripts/clavia-release.mjs                +1/-1

Bump all six package versions and include the new Bedrock test in packed-consumer checks. Rename an existing unused type-test parameter so the full typecheck passes.

Validation: 361 provider tests, 99 packed-consumer tests, full typecheck and lint, and six package builds pass. Request fixtures cover native images and PDFs, compatibility batching and attribution, Bedrock text history, and unchanged prompt inputs.