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)

packages/shared/src/index.ts

@@ -29,6 +29,7 @@ export const Activity = z.object({
   name: z.string(),
   insole_types: z.array(InsoleType),
   created_at: z.string(), // ISO-8601
+  sort_order: z.number().int(),
 });
 export type Activity = z.infer<typeof Activity>;
 
@@ -41,6 +42,11 @@ export type CreateActivityInput = z.infer<typeof CreateActivityInput>;
 export const UpdateActivityInput = CreateActivityInput;
 export type UpdateActivityInput = z.infer<typeof UpdateActivityInput>;
 
+export const ReorderActivitiesInput = z.object({
+  ids: z.array(z.number().int()).min(1),
+});
+export type ReorderActivitiesInput = z.infer<typeof ReorderActivitiesInput>;
+
 export const SessionStatus = z.enum(['active', 'completed', 'discarded']);
 export type SessionStatus = z.infer<typeof SessionStatus>;
 
@@ -56,6 +62,8 @@ export const WorkSession = z.object({
   start_time: z.string(), // ISO-8601
   end_time: z.string().nullable(),
   duration_seconds: z.number().int().nullable(),
+  paused_seconds: z.number().int(),
+  paused_at: z.string().nullable(), // ISO-8601; set while paused, null = running
   status: SessionStatus,
   source: z.enum(['app', 'manual']),
   notes: z.string().nullable(),