chore: update Stagehand light logo and Director icon to colored variants (browserbase#1970)

## Summary
- Replace the Stagehand light mode logo with the colored version (green
icon instead of all-black)
- Replace the Director icon with the new colored logomark (blue
geometric design)
- Updates both `packages/docs/logo/` and `media/` copies to stay in sync

## Test plan
- [ ] Verify the docs site shows the green Stagehand logo in light mode
- [ ] Verify the Director icon renders correctly where referenced

🤖 Generated with [Claude Code](https://claude.com/claude-code)

<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Replaced the Stagehand light-mode logo with its green-colored version
and updated the Director icon to the new blue logomark. Synced assets in
`media/` and `packages/docs/logo/` to keep the docs and site consistent.

<sup>Written for commit 4c151ec.
Summary will update on new commits. <a
href="https://cubic.dev/pr/browserbase/stagehand/pull/1970">Review in
cubic</a></sup>

<!-- End of auto-generated description by cubic. -->

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: shrey150