Tidy: deprecate + rename init/constructor

[kamath]

why

We have params being passed in to init that are also in the constructor. This is redundant and doesn't make sense. Cleaning this up. Also deprecating initFromPage in favor of browserbaseResumeSessionId. Lastly, change browserBase to browserbase.

Now you can just do

const stagehand = new Stagehand({ yourParams });
await stagehand.init()

what changed

param names + docs

test plan

evals CI

[changeset-bot]

🦋 Changeset detected

Latest commit: c0339b6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@browserbasehq/stagehand	Minor

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[ilias-t]

is there a migration guide somewhere for this change?

Deprecate initFromPage in favor of browserbaseResumeSessionID in constructor