#4534: fix: packaging and OpenAI vision format conversion

This PR addresses two issues: 1. **Fix missing bin field in package.json**: Resolves the Windows installer ENOENT error by correctly specifying the bin path without the leading `./` which can cause issues on some environments/installers. 2. **Add image format conversion in OpenAI-compatible API**: Extracts `media_type` from data URIs in OpenAI vision format and converts them to the format expected by the internal agent command, enabling vision model support via the OpenAI-compatible endpoint. Fixes #3787 and #3781. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates packaging metadata and the OpenAI-compatible HTTP gateway. - **Packaging:** fixes the `bin` entries in `package.json` to point at `moltbot.mjs` without a leading `./`, addressing Windows installer `ENOENT` scenarios where the relative prefix is misinterpreted. - **OpenAI gateway:** extends `src/gateway/openai-http.ts` to recognize OpenAI “vision” message parts (`content` arrays with `type: "image_url"`) by extracting `data:`-URI images (mimeType + base64 payload) and passing them through as `images?: ImageContent[]` into `agentCommand()` for both streaming and non-streaming requests. Overall, the change fits the codebase’s pattern of translating gateway payloads into the internal `agentCommand` input shape, but the new message filtering/parsing introduces a couple of behavior edge cases that can lead to empty prompts or silently dropped images. <h3>Confidence Score: 3/5</h3> - This PR is reasonably safe to merge, but the OpenAI gateway change likely introduces an input-validation regression that can produce empty prompts or degraded history. - The packaging change is low risk. The gateway change is small and localized, but the new role/content guard at src/gateway/openai-http.ts:107 appears incorrect versus the prior intent and can allow empty text messages into history / block image-only requests from working as intended. The remaining issues are compatibility/robustness gaps rather than outright crashes. - src/gateway/openai-http.ts <!-- greptile_other_comments_section --> <!-- /greptile_comment -->