fix(expenses): improve receipt amount extraction and vendor naming

- Remove card brands (VISA/MC/Amex) from _SKIP_LINE_RE so card-terminal
  lines like "VISA USD$ 36.78" are no longer skipped
- Replace bottom-50% scan with full-text max scan (Pass 2): scans every
  line in the receipt and returns the largest dollar amount, correctly
  handling display-style receipts that show the charge at the top with
  no label (e.g. LAYAL CAFE $40.10 before the item list)
- Update vendor LLM prompt to ask the model to correct OCR garbling
  (e.g. "NeDonald's" → "McDonald's") and detect bank statements
- Add 4 new tests covering top-amount, card-terminal, max-beats-items,
  and change-exclusion scenarios (71 tests, all passing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_expenses_agent.py

@@ -474,11 +474,33 @@ class TestExtractAmount:
         assert _extract_amount_from_text(text) == 5.50
 
     def test_amount_due_with_usd_suffix(self):
-        # PDF text may include "USD" after the number — regex should still work
-        # via the bottom scan since the labeled-total regex won't match "USD"
+        # "Total Charged" is in _TOTAL_RE — Pass 1 catches it
         text = 'Total Charged: $198.40 USD'
         assert _extract_amount_from_text(text) == 198.40
 
+    def test_top_amount_returned_by_max(self):
+        # Display-style receipt: charge shown at top, no 'Total' label.
+        # Pass 2 (max) must find $40.10 even though it is before the item list.
+        text = 'LAYAL CAFE\n$40.10\n--------\nBreakfast  37.30\nCoffee  2.80'
+        assert _extract_amount_from_text(text) == 40.10
+
+    def test_card_terminal_visa_line(self):
+        # Card terminal: amount on a line prefixed with card-brand text.
+        # VISA must NOT be in the skip list so the amount is captured.
+        text = 'MERCHANT XYZ\nYHOOMHXAKKKEO4S VISA USD$ 36.78\nAuth 123456'
+        assert _extract_amount_from_text(text) == 36.78
+
+    def test_max_beats_item_prices(self):
+        # Receipt with several item prices — max should return the largest
+        # (the total), not an item that appears last in the text.
+        text = 'Burger  12.99\nFries   4.50\nDrink   2.99\nT0TAL  20.48'
+        assert _extract_amount_from_text(text) == 20.48
+
+    def test_change_line_excluded_from_max(self):
+        # Change-due line must be skipped so it never inflates the max.
+        text = 'Items  8.49\nCash Tendered  20.00\nChange  11.51'
+        assert _extract_amount_from_text(text) == 8.49
+
 
 class TestExtractDate:
     def test_iso_format(self):