Add Race workout kind with Garmin eventType auto-detection, sync-time running filter, and pill-based review queue filter

Race is the 8th fixed workout kind, seeded with a real (not placeholder)
rule since Garmin Connect's eventType.typeKey reports "race" for
manually-tagged race activities. Non-running activity types (padel,
cycling, strength training, ...) are now dropped at sync time instead of
being stored. The Review Queue's type filter is now clickable exclusive
pill buttons instead of a dropdown.

frontend/src/App.css

@@ -137,6 +137,25 @@ button:disabled {
   cursor: default;
 }
 
+.filter-pills {
+  display: flex;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+  margin-bottom: 1rem;
+}
+
+.filter-pill {
+  border-radius: 999px;
+  padding: 0.35rem 0.9rem;
+  font-size: 0.85rem;
+}
+
+.filter-pill.active {
+  background: #3b82f6;
+  border-color: #3b82f6;
+  color: #fff;
+}
+
 .empty-state {
   color: #9aa0ab;
 }

frontend/src/pages/ReviewQueue.tsx

@@ -59,25 +59,41 @@ export function ReviewQueue() {
     return items.filter((item) => candidates(item).some((c) => c.workout_kind_id === id));
   }, [items, filterKindId]);
 
+  function toggleFilter(id: string) {
+    setFilterKindId((prev) => (prev === id ? "" : id));
+  }
+
   return (
     <div className="page">
       <h2>Review Queue</h2>
       {error && <p className="error">{error}</p>}
 
       {items.length > 0 && (
-        <div className="controls">
-          <label>
-            Filter
-            <select value={filterKindId} onChange={(e) => setFilterKindId(e.target.value)}>
-              <option value="">All ({items.length})</option>
-              <option value={UNSORTED}>Unsorted (no candidates)</option>
-              {kinds.map((k) => (
-                <option key={k.ID} value={k.ID}>
-                  {k.Name}
-                </option>
-              ))}
-            </select>
-          </label>
+        <div className="filter-pills">
+          <button
+            type="button"
+            className={`filter-pill${filterKindId === "" ? " active" : ""}`}
+            onClick={() => toggleFilter("")}
+          >
+            All ({items.length})
+          </button>
+          <button
+            type="button"
+            className={`filter-pill${filterKindId === UNSORTED ? " active" : ""}`}
+            onClick={() => toggleFilter(UNSORTED)}
+          >
+            Unsorted (no candidates)
+          </button>
+          {kinds.map((k) => (
+            <button
+              key={k.ID}
+              type="button"
+              className={`filter-pill${filterKindId === String(k.ID) ? " active" : ""}`}
+              onClick={() => toggleFilter(String(k.ID))}
+            >
+              {k.Name}
+            </button>
+          ))}
         </div>
       )}