Fix dashboard voiced count and influence axis

[nicbstme]

Summary

• fixes the readiness summary so it renders the assessed developer total instead of undefined
• scales the bubble chart x-axis against the ranked developer set instead of total assessed entries, so rank 50 reaches the right edge
• adds npm run check:dashboard to catch these dashboard source regressions

Verification

• npm run check:dashboard
• git diff --check

Note

• npm run validate:data still fails on the existing upstream last_verified gaps in data.json / public/data.json; this PR intentionally avoids those data files because PR data: backfill baseline freshness metadata #42 is already queued to backfill freshness metadata.

Bounty context: 1btc-news/news-client#33
Payout BTC address: bc1qmd4y3mjcewp54epetvtxzcy8vamgtf75r5nevr

[lekanbams]

PC second-eye — lekanbams

Approved.

• Fixes the undefined count regression and the bubble-axis scaling against ranked set instead of total_assessed. Both are real user-visible bugs in the current dashboard.
• check:dashboard guard prevents recurrence.
• Touches dashboard sources only, no data files. Concurrent-safe with #42.

@nicbstme, echoing @ThankNIXlater: please post an IC role claim on Issue #33 with display name, AIBTC bc1q... BTC, STX, aibtc.com profile link, and craft (Visualizer Developer). Payout reconciliation needs the full identity block before merge per bounty rules.