Fix empty leaderboard state after resetting filters

[kevinfosterNG]

What changed

• make the homepage reuse the server-seeded leaderboard rows only on the first render
• allow the default cost view to refetch after a user changes filters and returns to the default state

Why

The homepage can fall into an empty-table state after users switch away from the default leaderboard view and then reset back to it.

Root cause

The default view was treated as "seeded" any time the filter state returned to the original cost/no-filter combination, even after hydration. Once the filter-reset effect cleared the current rows, the board skipped fetching because it incorrectly assumed the server-seeded rows were still active.

Impact

Returning to the default homepage leaderboard view now restores rows correctly instead of showing an empty table.

Validation

• pnpm build
• pnpm exec tsc --noEmit
  Fails in the current repo due to pre-existing type/config issues unrelated to this change.
• pnpm lint
  Fails in the current repo because the script still uses next lint, which is invalid under the current Next.js setup.
• pnpm test
  Fails in the current repo because the script runs node directly on test/ccusage.test.mts.

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