fix: Resolve all lint warnings and type errors across frontend and backend.

Frontend:
- Memoize pagination object in TransactionsTable to prevent unnecessary re-renders and fix exhaustive-deps warning
- Add optional success and message fields to backup API response types for proper error handling

Backend:
- Add TypedDict for transaction type configuration to improve type safety in generate_sample_db
- Fix unpacking of amount_range with explicit float type hints
- Add explicit type hints for descriptions dictionary and specific_descriptions variable
- Fix sync endpoint return types: get_sync_status returns SyncStatus and sync_now returns SyncResult
- Fix transactions endpoint data type declaration to properly support Union types in PaginatedResponse

All checks now pass:
- Frontend: npm lint and npm build ✓
- Backend: mypy type checking ✓
- Backend: ruff lint on modified files ✓

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

leggen/api/models/common.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Generic, List, TypeVar
+from typing import Generic, List, TypeVar
 
 from pydantic import BaseModel
 

leggen/api/routes/accounts.py

@@ -246,11 +246,6 @@ async def get_account_transactions(
             offset=offset,
         )
 
-        # Get total count for pagination info
-        total_transactions = await database_service.get_transaction_count_from_db(
-            account_id=account_id,
-        )
-
         data: Union[List[TransactionSummary], List[Transaction]]
 
         if summary_only:
@@ -299,9 +294,7 @@ async def get_account_transactions(
 
 
 @router.put("/accounts/{account_id}")
-async def update_account_details(
-    account_id: str, update_data: AccountUpdate
-) -> dict:
+async def update_account_details(account_id: str, update_data: AccountUpdate) -> dict:
     """Update account details (currently only display_name)"""
     try:
         # Get current account details

leggen/api/routes/backup.py

@@ -129,9 +129,7 @@ async def test_backup_connection(test_request: BackupTest) -> dict:
         success = await backup_service.test_connection(s3_config)
 
         if not success:
-            raise HTTPException(
-                status_code=400, detail="S3 connection test failed"
-            )
+            raise HTTPException(status_code=400, detail="S3 connection test failed")
 
         return {"connected": True}
 
@@ -193,9 +191,7 @@ async def backup_operation(operation_request: BackupOperation) -> dict:
             success = await backup_service.backup_database(database_path)
 
             if not success:
-                raise HTTPException(
-                    status_code=500, detail="Database backup failed"
-                )
+                raise HTTPException(status_code=500, detail="Database backup failed")
 
             return {"operation": "backup", "completed": True}
 
@@ -213,9 +209,7 @@ async def backup_operation(operation_request: BackupOperation) -> dict:
             )
 
             if not success:
-                raise HTTPException(
-                    status_code=500, detail="Database restore failed"
-                )
+                raise HTTPException(status_code=500, detail="Database restore failed")
 
             return {"operation": "restore", "completed": True}
         else:

leggen/api/routes/sync.py

@@ -3,7 +3,7 @@ from typing import Optional
 from fastapi import APIRouter, BackgroundTasks, HTTPException
 from loguru import logger
 
-from leggen.api.models.sync import SchedulerConfig, SyncRequest
+from leggen.api.models.sync import SchedulerConfig, SyncRequest, SyncResult, SyncStatus
 from leggen.background.scheduler import scheduler
 from leggen.services.sync_service import SyncService
 from leggen.utils.config import config
@@ -13,7 +13,7 @@ sync_service = SyncService()
 
 
 @router.get("/sync/status")
-async def get_sync_status() -> dict:
+async def get_sync_status() -> SyncStatus:
     """Get current sync status"""
     try:
         status = await sync_service.get_sync_status()
@@ -78,7 +78,7 @@ async def trigger_sync(
 
 
 @router.post("/sync/now")
-async def sync_now(sync_request: Optional[SyncRequest] = None) -> dict:
+async def sync_now(sync_request: Optional[SyncRequest] = None) -> SyncResult:
     """Run sync synchronously and return results (slower, for testing)"""
     try:
         if sync_request and sync_request.account_ids:

leggen/api/routes/transactions.py

@@ -64,11 +64,9 @@ async def get_all_transactions(
             search=search,
         )
 
-        data: Union[List[TransactionSummary], List[Transaction]]
-
         if summary_only:
             # Return simplified transaction summaries
-            data = [
+            data: list[TransactionSummary | Transaction] = [
                 TransactionSummary(
                     transaction_id=txn["transactionId"],  # NEW: stable bank-provided ID
                     internal_transaction_id=txn.get("internalTransactionId"),