Replace per-kind reclassify with a single global reclassify that respects manual and Race locks

Manual assignments are the user's definitive word and Race assignments come
from a hard Garmin fact (eventType.typeKey), not a retunable rule -- neither
is ever touched by reclassify again, and Race can no longer be set by hand
via the review queue. Adds an Activities page so this locked/unlocked status
is visible per workout, since Review Queue only ever showed unresolved items.

frontend/src/types/api.ts

@@ -47,6 +47,14 @@ export interface Lap {
   HRRecoveryBpmPerMin: number | null;
 }
 
+export interface ActivityListItem extends Activity {
+  workout_kind_id: number | null;
+  workout_kind_name: string | null;
+  assignment_source: "rule_engine" | "manual" | null;
+  assignment_status: "assigned" | "needs_review" | null;
+  locked: boolean;
+}
+
 export interface WorkoutKind {
   ID: number;
   Name: string;