sortByDate: invalid date strings produce NaN comparator results (undefined sort order)

[ManningWorks]

Problem

sortByDate resolves each project's date as updatedAt || createdAt || null, then converts via new Date(date).getTime(). A truthy-but-unparseable string (e.g. "not-a-date") yields NaN, so the comparator returns NaN and the resulting order is unspecified per the ECMAScript sort contract.

// packages/core/src/lib/sortByDate.ts
const timeA = dateA ? new Date(dateA).getTime() : 0  // 'not-a-date' → NaN
return (timeA - timeB) * multiplier                  // NaN

Context

• Pre-existing behaviour — not a regression from sortByDate sorts null/missing dates to the TOP in descending order #23 / PR fix(sort): treat null dates as oldest in sortByDate #27 — surfaced during that PR's review.
• Dates originate from the GitHub/npm/dev.to APIs and manual config, so it is unlikely to bite in practice.

Proposal

Coerce NaN to 0 in the comparator so unparseable dates degrade to dateless (epoch-equivalent, oldest) rather than poisoning the sort:

const timeA = dateA ? new Date(dateA).getTime() || 0 : 0

(|| 0 also swallows a literal epoch 0, which is acceptable — it already ties with dateless per #23.)