Un-mock the Timesheet screen and wire it to the Timesheet API (GA-008)

[Rana7xi]

What this does

The Timesheet screen was reading from the attendance endpoint and working
out the hours on the phone, which ignored break time. It now loads from the
Timesheet API and shows the hours the backend already works out.

Changes

• New API client for the timesheet endpoints
• The screen loads from GET /timesheets instead of GET /attendance/:userId
• Hours come from the backend, nothing is calculated on the phone
• New Timesheet Details screen loads one record from GET /timesheets/:id
• Loading, error and empty are separate states, with a retry button on error
• Added the new text to all six language files

Testing

Tested on the Android emulator with two completed shifts, one normal day
shift and one that runs overnight across midnight. The hours on screen match
the API response. The detail view opens and the empty state works.
Type check, lint and format all pass.

[Krisha190235]

The code is correct and I verified the backend contract fully matches (serializer fields, list {page,limit,total,timesheets}, both routes, guard-token scoping). It's also a cleaner, more complete implementation than the earlier timesheet work — proper endpoint, detail screen, totals, error/retry, i18n. The three notes I raised (pagination cap, formatHours decimals, UTC/local dates) are cosmetic follow-ups, not merge blockers.