F14: add per-activity delete (DELETE /api/activity/{id} + drawer button)

Server endpoint removes the activity JSON, GeoJSON, timeseries, sidecar
edit, and images directory. Also purges the dedup cache entry so the
file can be re-uploaded if needed. Runs merge_all + rebuild afterwards.

EditDrawer: two-click delete button (click once → "Confirm delete?",
click again → deletes). On success, dispatches 'deleted' event.
ActivityDetail navigates back to the feed on delete.

site/src/components/ActivityDetail.svelte

@@ -112,7 +112,7 @@
 <svelte:window on:keydown={onKeydown} />
 
 {#if editOpen && editEnabled}
-  <EditDrawer activityId={activity.id} {editUrl} on:saved={onSaved} on:close={() => editOpen = false} />
+  <EditDrawer activityId={activity.id} {editUrl} on:saved={onSaved} on:close={() => editOpen = false} on:deleted={() => { window.location.href = base; }} />
 {/if}
 
 <!-- Lightbox -->

site/src/components/EditDrawer.svelte

@@ -5,7 +5,7 @@
   export let activityId: string;
   export let editUrl: string;
 
-  const dispatch = createEventDispatcher<{ saved: { title: string; description: string }; close: void }>();
+  const dispatch = createEventDispatcher<{ saved: { title: string; description: string }; close: void; deleted: void }>();
 
   const SPORTS: Sport[] = ['cycling', 'running', 'hiking', 'walking', 'swimming', 'skiing', 'other'];
   const STAT_PANELS = [
@@ -21,6 +21,8 @@
   let saving = false;
   let saveStatus = '';
   let saveOk = false;
+  let confirmDelete = false;
+  let deleting = false;
 
   // Form state
   let title = '';
@@ -120,6 +122,22 @@
       : [...hideStats, key];
   }
 
+  async function deleteActivity() {
+    if (!confirmDelete) { confirmDelete = true; return; }
+    deleting = true;
+    try {
+      const res = await fetch(api, { method: 'DELETE' });
+      if (!res.ok) throw new Error(await res.text());
+      dispatch('deleted');
+    } catch (e: any) {
+      saveStatus = `Delete failed: ${e.message}`;
+      saveOk = false;
+      confirmDelete = false;
+    } finally {
+      deleting = false;
+    }
+  }
+
   load();
 </script>
 
@@ -284,11 +302,26 @@
     <div class="px-5 py-4 border-t border-zinc-800 flex items-center gap-3 shrink-0">
       <button
         class="px-4 py-2 bg-blue-600 hover:bg-blue-500 disabled:opacity-40 text-white text-sm font-medium rounded-lg transition-colors"
-        disabled={saving}
+        disabled={saving || deleting}
         on:click={save}
       >
         {saving ? 'Saving…' : 'Save'}
       </button>
+      <button
+        class="px-3 py-2 text-sm font-medium rounded-lg border transition-colors disabled:opacity-40 ml-auto"
+        class:border-zinc-700={!confirmDelete}
+        class:text-zinc-500={!confirmDelete}
+        class:hover:border-red-600={!confirmDelete}
+        class:hover:text-red-400={!confirmDelete}
+        class:border-red-500={confirmDelete}
+        class:text-red-400={confirmDelete}
+        class:bg-red-950={confirmDelete}
+        disabled={deleting}
+        on:click={deleteActivity}
+        on:blur={() => confirmDelete = false}
+      >
+        {deleting ? 'Deleting…' : confirmDelete ? 'Confirm delete?' : 'Delete'}
+      </button>
       {#if saveStatus}
         <span class="text-xs" class:text-green-400={saveOk} class:text-red-400={!saveOk}>
           {saveStatus}