Add Playwright integration specification for browser testing in execution environments (#156)

* Initial plan

* Add comprehensive Playwright integration specification document

Co-authored-by: notfolder <20558197+notfolder@users.noreply.github.com>

* Address review feedback: remove unnecessary sections, add Java/Go Playwright variants, dynamic MCP addition

Co-authored-by: notfolder <20558197+notfolder@users.noreply.github.com>

* Update Playwright MCP startup method to match text-editor MCP approach

Co-authored-by: notfolder <20558197+notfolder@users.noreply.github.com>

* Remove Python code examples, keep only processing descriptions and docker exec command

Co-authored-by: notfolder <20558197+notfolder@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: notfolder <20558197+notfolder@users.noreply.github.com>

Author: Copilot