local activity storage and convert page fixes

- Replace rdp dependency with inline pure-Python RDP implementation
    so the bincio wheel runs in Pyodide (no pure-Python wheel existed for rdp)
  - Fix convert page script: remove define:vars so Vite bundles it and
    TypeScript imports (localstore, format) work correctly
  - Rename wheel to proper PEP 427 filename (bincio-0.1.0-py3-none-any.whl)
  - Use en-GB date format on convert result, consistent with the feed
  - Add /activity/local/ page + LocalActivityDetail for IDB-only activities;
    feed links local activities there instead of the SSG route
  - Fix getStaticPaths: try public/data symlink as fallback, never crash on
    missing index.json
  - Fix ActivityDetail.onMount: load detail even when detail_url is absent
    so locally converted activities show map and charts
  - Derive track_url and detail_url from id in toSummary() since they are
    not present in the detail JSON
  - Reload on bfcache restore (pageshow) so client:only components re-mount
    after back navigation

site/src/components/ActivityDetail.svelte

@@ -27,9 +27,8 @@
   $: displayTitle = localTitle || activity.title;
 
   onMount(async () => {
-    if (!activity.detail_url) return;
     try {
-      detail = await loadActivity(activity.id, activity.detail_url, base);
+      detail = await loadActivity(activity.id, activity.detail_url ?? '', base);
       if (!detail) throw new Error('Activity not found');
     } catch (e: any) {
       error = e.message;

site/src/components/ActivityFeed.svelte

@@ -111,7 +111,7 @@
   <div class="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
     {#each visible as a (a.id)}
       <a
-        href={`${import.meta.env.BASE_URL}activity/${a.id}/`}
+        href={a.detail_url ? `${import.meta.env.BASE_URL}activity/${a.id}/` : `${import.meta.env.BASE_URL}activity/local/?id=${a.id}`}
         class="block rounded-xl bg-zinc-900 border border-zinc-800 p-4 hover:border-zinc-600 hover:bg-zinc-800/80 transition-all group"
       >
         <!-- header -->

site/src/components/LocalActivityDetail.svelte

@@ -0,0 +1,27 @@
+<script lang="ts">
+  import { onMount } from 'svelte';
+  import { getLocalActivity } from '../lib/localstore';
+  import type { ActivitySummary } from '../lib/types';
+  import ActivityDetail from './ActivityDetail.svelte';
+
+  export let base: string = '/';
+
+  let activity: ActivitySummary | null = null;
+  let error = '';
+
+  onMount(async () => {
+    const id = new URLSearchParams(window.location.search).get('id');
+    if (!id) { error = 'No activity ID in URL.'; return; }
+    const found = await getLocalActivity(id);
+    if (!found) { error = `Activity "${id}" not found on this device.`; return; }
+    activity = found;
+  });
+</script>
+
+{#if error}
+  <p class="text-red-400 text-sm py-12 text-center">{error}</p>
+{:else if activity}
+  <ActivityDetail {activity} {base} athlete={null} />
+{:else}
+  <div class="h-32 rounded-xl bg-zinc-900 border border-zinc-800 animate-pulse mt-4"></div>
+{/if}