timesheet_entries, fuel_logs and delivery_notes had no indexes at all --
fine at today's row counts, not once site count grows toward the 18-20
target. Added 8 indexes across fuel_logs, timesheet_entries,
delivery_notes, purchase_orders and plant_hours_log, unioned into each
collection's existing index array rather than replacing it.
Verified both pre-existing UNIQUE indexes (idx_po_number, load-bearing
for the placeholder-PO-number scheme; idx_plant_hours_log_qr_start,
prevents duplicate weekly imports) are byte-for-byte unchanged.
Idempotent: a second run touches nothing.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
13f76ac894