feat: AI-generated skincare routine suggestions (single + batch)

Add Gemini-powered endpoints and frontend pages for proposing skincare
routines based on skin state, product compatibility, grooming schedule,
and recent history.

Backend (routines.py):
- POST /routines/suggest — single AM/PM routine for a date
- POST /routines/suggest-batch — AM+PM plan for up to 14 days
- Prompt context: skin snapshot, grooming schedule, 7-day history,
  filtered product list with effects/incompatibilities/context rules
- Respects retinoid frequency limits, acid/retinoid separation,
  grooming-aware safe_after_shaving rules

Frontend:
- /routines/suggest page with tab switcher (single / batch)
- Single tab: date + AM/PM + optional notes → generate → preview → save
- Batch tab: date range + notes → collapsible day cards (AM+PM) → save all
- Loading spinner during Gemini calls; product names resolved from map
- "Zaproponuj rutynę AI" button added to routines list page

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -1,16 +1,19 @@
 import { PUBLIC_API_BASE } from '$env/static/public';
 import type {
 	ActiveIngredient,
+	BatchSuggestion,
 	GroomingSchedule,
 	LabResult,
 	MedicationEntry,
 	MedicationUsage,
+	PartOfDay,
 	Product,
 	ProductContext,
 	ProductEffectProfile,
 	ProductInteraction,
 	ProductInventory,
 	Routine,
+	RoutineSuggestion,
 	RoutineStep,
 	SkinConditionSnapshot
 } from './types';
@@ -130,6 +133,18 @@ export const updateRoutineStep = (stepId: string, body: Record<string, unknown>)
 export const deleteRoutineStep = (stepId: string): Promise<void> =>
 	api.del(`/routines/steps/${stepId}`);
 
+export const suggestRoutine = (body: {
+	routine_date: string;
+	part_of_day: PartOfDay;
+	notes?: string;
+}): Promise<RoutineSuggestion> => api.post('/routines/suggest', body);
+
+export const suggestBatch = (body: {
+	from_date: string;
+	to_date: string;
+	notes?: string;
+}): Promise<BatchSuggestion> => api.post('/routines/suggest-batch', body);
+
 export const getGroomingSchedule = (): Promise<GroomingSchedule[]> =>
 	api.get('/routines/grooming-schedule');
 export const createGroomingScheduleEntry = (body: Record<string, unknown>): Promise<GroomingSchedule> =>