Render Premium Analytics inside the wp-admin shell

[retrofox]

Proposed changes

• Register the Premium Analytics admin menu against the wp-build "wp-admin integrated" page variant (jetpack-premium-analytics-wp-admin) instead of the full-page slug. The page now renders inside the native wp-admin shell (sidebar + header) rather than the app taking over the whole screen via the admin_init interceptor.
• The menu callback points at the generated jpa_jetpack_premium_analytics_wp_admin_render_page() (from build/pages/jetpack-premium-analytics/page-wp-admin.php), guarded by function_exists() with a __return_null fallback when the build is absent.
• The full-page variant stays reachable directly at ?page=jetpack-premium-analytics; only the menu entry switches to the in-shell variant.

Closes WOOA7S-1572

Related product discussion/links

• WOOA7S-1572

Does this pull request change what data or activity we track or use?

No.

Testing instructions

• Build the package if needed: jetpack build packages/premium-analytics.
• In wp-admin, open the Analytics menu entry.
• Confirm the dashboard renders inside the standard wp-admin chrome: the admin sidebar and header stay visible and the page no longer takes over the full screen.
• Confirm deep links still work, e.g. ?page=jetpack-premium-analytics-wp-admin&p=/ loads the dashboard route.

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/packages/premium-analytics/src/class-analytics.php	4/54 (7.41%)	-0.44%	3 ❤️‍🩹

Full summary · PHP report