Select multiple transactions and update them all at once - saves time when managing similar transactions.
Features:
• Multi-select with checkboxes (Shift+Click for range selection)
• Bulk edit modal to update: Category, Notes (append/replace), Transfer nature, Payment type
• “All-or-none” strategy - no partial updates
• Progress indicator for large batches
• Reuses existing multi-select pattern from Budgets feature
New API endpoint: PUT /api/v1/transactions/bulk
Constraints: Only supports marking as non-transfer or transfer-out; external account transactions have restricted edits.
