Add break time feature to time entries

- Add breakMinutes field to TimeEntry model and database migration
- Users can now add break duration (minutes) to time entries
- Break time is subtracted from total tracked duration
- Validation ensures break time cannot exceed total entry duration
- Statistics and client target balance calculations account for breaks
- Frontend UI includes break time input in TimeEntryFormModal
- Duration displays show break time deduction (e.g., '7h (−1h break)')
- Both project/client statistics and weekly balance calculations updated

backend/src/types/index.ts

@@ -38,6 +38,7 @@ export interface UpdateProjectInput {
 export interface CreateTimeEntryInput {
   startTime: string;
   endTime: string;
+  breakMinutes?: number;
   description?: string;
   projectId: string;
 }
@@ -45,6 +46,7 @@ export interface CreateTimeEntryInput {
 export interface UpdateTimeEntryInput {
   startTime?: string;
   endTime?: string;
+  breakMinutes?: number;
   description?: string;
   projectId?: string;
 }