Support configuring a default effort level

[charlesvien]

Context

Users want to set a default effort level for PostHog Code sessions. Currently the app does not respect the effort level configured in their Claude settings.

Problem

There is no way to configure a default effort level in PostHog Code. Users who have set a preferred effort level in their Claude settings expect that preference to carry over, but it is not respected.

Expected behavior

PostHog Code should either:

• Respect the effort level set in the user's Claude settings, or
• Provide its own setting to configure a default effort level