Fix coordinate formatting consistency and empty filter state handling

[Copilot]

Coordinate values in CrossSearchTable displayed excessive decimal precision inconsistent with LocalityTable. Empty filter values polluted URL state and server queries.

Changes

• Coordinate formatting: Added formatWithMaxThreeDecimals formatter to dec_lat and dec_long columns in CrossSearchTable, matching LocalityTable behavior. Handles both numeric and string coordinate values.

• Filter state sanitization: TableView now excludes empty filter values (empty strings, null, undefined, empty arrays) from URL state and server-side queries via sanitizeColumnFilters.

• Test coverage: Added LocalityTable tests verifying coordinate formatting preserves values ≤3 decimals and truncates longer values. CrossSearchTable tests added for parity.

// Before: 12.3456789 displayed as-is
// After: 12.3456789 → "12.346", 12.3 → 12.3

const formatWithMaxThreeDecimals = (value: unknown): number | string => {
  const numericValue = typeof value === 'number' ? value : typeof value === 'string' ? Number(value) : Number.NaN
  if (!Number.isFinite(numericValue)) return ''
  if (decimalCount(numericValue) > 3) return numericValue.toFixed(3)
  return numericValue
}

Note: formatWithMaxThreeDecimals and decimalCount are duplicated across both table components - could be extracted to shared utility in follow-up.

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