Add overview and top list tabs to the data page

[bluebird42]

The data page only showed space-wide totals, so there was no way to see which videos drive the views. The page now reuses the settings tab bar with two tabs:

• Overview (/data) keeps the existing numbers, history and sources unchanged.
• Top list (/data/top-list) ranks the space's 25 most viewed videos this year, with each row linking to the video.

Views per video use the same definition as the overview: a session counts once it has watched at least one second. The new Analytics.space_top_videos/2 query groups by embed and session, and Embeds.dashboard_videos_by_hash/2 resolves names and dashboard ids within the current space only. Deleted videos keep their events, so the query fetches up to 50 rows and the page drops anything that no longer resolves before taking the top 25. The shared trial space returns an empty list, matching space_data/1. When a space cannot view statistics, the existing notice moves into the tab bar and both tabs show empty states.

Both scoped (/:space_id/data/top-list) and unscoped routes are added, and DashboardRoutes.data_top_list_path/2 builds them.

Overview tab:

Top list tab (synthetic data):

Validation:

• New LiveView tests cover the tab links and patch navigation, and rank two videos by views while leaving out a deleted video with more views; the existing data page tests pass.
• mix compile --warnings-as-errors, mix format --check-formatted and Credo passed.
• Checked both tabs in the development stack with synthetic events sent through /v1/events.

No migration is needed; the query reads the existing events table.