Add interactive routine wizard, slider controls, value persistence, and timer pause

- Interactive routine generation wizard with AI refinement loop (generate-draft,
  refine, save-draft endpoints + RoutineWizard modal component)
- Replace +/- stepper buttons with slider controls for reps/weight during workout
- Persist user-modified reps/weight across sets of the same exercise
- Add pause/resume by tapping timer dials, with back-button confirmation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/api/kettlebell.ts

@@ -1,5 +1,5 @@
 import client from './client';
-import type { KettlebellSession, KettlebellSetLog } from '../types/kettlebell';
+import type { KettlebellSession, KettlebellSetLog, DraftSession } from '../types/kettlebell';
 
 export interface GenerateSessionRequest {
     focus: string;
@@ -7,6 +7,18 @@ export interface GenerateSessionRequest {
     available_weights: number[];
 }
 
+export interface RefineRequest {
+    draft: DraftSession;
+    feedback: string;
+    focus: string;
+    duration_minutes: number;
+    available_weights: number[];
+}
+
+export interface SaveDraftRequest {
+    draft: DraftSession;
+}
+
 export interface LogSetRequest {
     exercise_order: number;
     set_number: number;
@@ -49,3 +61,12 @@ export const abandonSession = (id: number) =>
 
 export const deleteSession = (id: number) =>
     client.delete(`/kettlebell/${id}`);
+
+export const generateDraft = (data: GenerateSessionRequest) =>
+    client.post<DraftSession>('/kettlebell/generate-draft', data).then(r => r.data);
+
+export const refineDraft = (data: RefineRequest) =>
+    client.post<DraftSession>('/kettlebell/refine', data).then(r => r.data);
+
+export const saveDraft = (data: SaveDraftRequest) =>
+    client.post<KettlebellSession>('/kettlebell/save-draft', data).then(r => r.data);