Add bundle analyzer route summary (#98787)
### What?
Add a route summary homepage to the Turbopack bundle analyzer and move
individual route analysis to `/analyze`.
Precompute raw, compressed, and client bundle sizes for every route in
Rust and emit them in one `route-summaries.json` payload. Use that
payload to rank the largest client routes, label the route picker, and
calculate route deltas in comparisons.
### Why?
Opening the analyzer at `/` previously showed an empty treemap until a
route was selected. Loading route sizes also required fetching every
route's `analyze.data` payload.
### How?
- Show the 15 largest client payloads with progressive disclosure and
route search.
- Keep route rows as links so they support browser navigation and
opening in a new tab.
- Use dedicated loading UI for the summary page.
- Keep comparison controls on route analysis pages where a route is
selected.
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Co-authored-by: vercel-fleet-prod[bot] <318278635+vercel-fleet-prod[bot]@users.noreply.github.com>
Co-authored-by: Will Binns-Smith <755844+wbinnssmith@users.noreply.github.com>
