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/schemas/index.ts

@@ -31,6 +31,7 @@ export const UpdateProjectSchema = z.object({
 export const CreateTimeEntrySchema = z.object({
   startTime: z.string().datetime(),
   endTime: z.string().datetime(),
+  breakMinutes: z.number().int().min(0).optional(),
   description: z.string().max(1000).optional(),
   projectId: z.string().uuid(),
 });
@@ -38,6 +39,7 @@ export const CreateTimeEntrySchema = z.object({
 export const UpdateTimeEntrySchema = z.object({
   startTime: z.string().datetime().optional(),
   endTime: z.string().datetime().optional(),
+  breakMinutes: z.number().int().min(0).optional(),
   description: z.string().max(1000).optional(),
   projectId: z.string().uuid().optional(),
 });