Guard Stagehand runtime compatibility

[garaekz]

Summary

Fixes the Stagehand/package version drift that allowed the Laravel package to install a stale runtime binary without the serve flags required by current package code.

What changed

• Adds a Stagehand binary compatibility guard during runtime install.
• Rejects stale Stagehand binaries missing required serve flags instead of accepting them silently.
• Aligns package, runtime, smoke, and release-note surfaces to v1.0.2.
• Fixes Windows binary resolution for absolute drive-letter paths and runnable .exe/.cmd/.bat files.
• Namespaces Chromium profiles per Stagehand process so stale Chrome children cannot lock a restarted runtime out of rendering.
• Fixes the browser-pool timeout race that could return a fresh lease with a cancelled browser context.

Verification

• composer test in packages/laravel: 55 passed, 208 assertions.
• go test ./... -timeout 120s -p 1 from a temp copy of runtime/stagehand: passed.
• git diff --check: passed.