feat(shared,api): add pause + sort_order columns and contracts

Adds server-side pause accounting and activity ordering primitives.
- WorkSession contract gains paused_seconds (number) and paused_at (ISO string | null).
- Activity contract gains sort_order (number); new ReorderActivitiesInput zod.
- work_sessions += paused_seconds (int NOT NULL DEFAULT 0) + paused_at (timestamp_ms nullable).
- activities += sort_order (int NOT NULL DEFAULT 0).
- toWorkSession / toActivity map the new fields; generated migration 0003.

The new fields are additive; existing api/worker/admin tests stay green.

Products affected: SoleLog backend (apps/api), shared contracts (packages/shared)

apps/api/test/work-session.test.ts

@@ -0,0 +1,39 @@
+import { describe, it, expect } from 'vitest';
+import { toWorkSession } from '../src/lib/work-session';
+import type { workSessions } from '../src/db/schema';
+
+type WorkSessionRow = typeof workSessions.$inferSelect;
+
+function baseRow(overrides: Partial<WorkSessionRow> = {}): WorkSessionRow {
+  return {
+    id: 1,
+    userId: 'user-1',
+    activityId: 1,
+    insoleType: 'Kurk',
+    pairCount: 2,
+    startTime: new Date('2026-06-17T08:00:00.000Z'),
+    endTime: null,
+    durationSeconds: null,
+    pausedSeconds: 0,
+    pausedAt: null,
+    status: 'active',
+    source: 'app',
+    notes: null,
+    createdAt: new Date('2026-06-17T08:00:00.000Z'),
+    ...overrides,
+  };
+}
+
+describe('toWorkSession paused fields', () => {
+  it('maps pausedSeconds and a null pausedAt', () => {
+    const result = toWorkSession(baseRow({ pausedSeconds: 120, pausedAt: null }));
+    expect(result.paused_seconds).toBe(120);
+    expect(result.paused_at).toBeNull();
+  });
+
+  it('maps a pausedAt Date to its ISO string', () => {
+    const pausedAt = new Date('2026-06-17T08:05:00.000Z');
+    const result = toWorkSession(baseRow({ pausedSeconds: 0, pausedAt }));
+    expect(result.paused_at).toBe(pausedAt.toISOString());
+  });
+});