feat(browser): add upload command and fix producthunt hot

[hanzili]

Summary

• Add a generic opencli browser upload <target> <files...> command for setting local files on resolved <input type="file"> elements.
• Validate file existence, target type, multi-file support, and return structured JSON upload metadata.
• Fix producthunt hot by removing an unnecessary network-capture wait before DOM scraping.

Why

The extension/page layer already supports file-input uploads, but the CLI did not expose a generic command. This makes media workflows for browser-backed adapters possible without platform-specific upload code.

producthunt hot could fail waiting for network capture even though the command only needs DOM data. A normal page wait is enough and avoids the brittle capture dependency.

Test plan

• npm run typecheck
• npm run build
• OPENCLI_DAEMON_PORT=19999 npm test
• node dist/src/main.js browser upload 2 /tmp/opencli-linkedin-test/transparent-1x1.png /tmp/opencli-linkedin-test/test-video.mp4
• node dist/src/main.js producthunt hot --limit 3

Manual validation

• Verified browser upload on a local file-input fixture.
• Verified LinkedIn image post flow with the new command using a real JPEG test image in Hanzi's logged-in browser session, after explicit approval for test posts.