docs: add /progress page with live stats cards and update navigation and component imports

apps/docs/lib/stats.ts

@@ -3,9 +3,9 @@
  * browser so `blume build` never depends on the API being up. API_BASE is the
  * deployed Worker — do not inline it anywhere else.
  *
- * Four islands read this (SolvedRing, SubmissionHeatmap, RecentSolves,
- * TopicBubbles). Each hydrates on its own, but they share this module, so the
- * one in-flight request is shared too: the page asks the Worker once.
+ * The five cards on pages/progress.astro read this (components/progress/).
+ * Each hydrates on its own, but they share this module, so the one in-flight
+ * request is shared too: the page asks the Worker once.
  *
  * Invariants: a malformed body is an error state, never a throw; the first
  * frame is always the loading state, so server and client render identically.