fix: prevent NaN rendering and normalize parseInt parsing across numeric displays

[Dexterity104]

Summary

Adds the missing numeric fallbacks so cells with missing or non-numeric values render as 0 instead of the literal string NaN, and brings a handful of parseInt call sites in line with the parseInt(value || '0', 10) pattern used elsewhere.

Closes #253

Changes

src/components/miners/MinerPRsTable.tsx

Three parseFloat calls in the score column were missing the || '0' fallback. A missing pr.score or pr.collateralScore rendered as NaN. Added the fallback to all three.

src/components/repositories/RepositoryStats.tsx

The "Available Rewards" and "Total Paid Out" rows rendered NaN α when totalAvailable / totalPaidOut were not parseable. Wrapped both with (parseFloat(value) || 0).toLocaleString(...), matching the guarded pattern used in IssuesList, IssueHeaderCard, and IssueStats.

src/components/leaderboard/TopRepositoriesTable.tsx

parseInt(searchParams.get('rows') || '', 10) returns NaN when the param is absent, only accidentally rescued by downstream validation. Swapped the '' fallback for '0' on both the rows and page lines so the fallback is intentional.

src/pages/PRDetailsPage.tsx

Added the 10 radix to all five parseInt(pullRequestNumber) calls for consistency with the rest of the codebase.

src/components/dashboard/CommitTrendChart.tsx

Added the 10 radix to parseInt(item.linesCommitted).

[anderdc]

Closing — the main NaN fixes from #253 (MinerPRsTable, TopRepositoriesTable) aren't in the diff, and the RepositoryStats change replaces formatTokenAmount (which already handles null/NaN) with a worse inline version. The remaining radix additions are harmless but not worth a PR on their own.