Support Hexadecimal Page Numbers (e.g. 1FF, 12E)

- Refactored  to parse page numbers as nibbles ((T<<4)|U) instead of decimal, preventing collisions between hex and decimal pages.
- Updated  to format page IDs as Hex.
- Updated  to display page IDs as Hex in the list.
- Ensures filler/housekeeping pages are correctly isolated.

src/teletext/io.py

@@ -191,7 +191,13 @@ def parse_header(data: bytearray):
     pu = decode_hamming_8_4(data[0])
     pt = decode_hamming_8_4(data[1])
     
-    page_num = (pt & 0xF) * 10 + (pu & 0xF)
+    # Use BCD/Hex-like storage: High nibble is Tens, Low nibble is Units.
+    # This preserves Hex pages (A-F) without colliding with decimal pages.
+    # E.g. Page 1FF -> Tens=F(15), Units=F(15) -> 0xFF (255)
+    # Page 12E -> Tens=2, Units=E(14) -> 0x2E (46)
+    # Page 134 -> Tens=3, Units=4 -> 0x34 (52)
+    # 0x2E != 0x34. No collision.
+    page_num = ((pt & 0xF) << 4) | (pu & 0xF)
     
     # Subcode: S1, S2, S3, S4
     # S1 (low), S2, S3, S4 (high)

src/teletext/models.py

@@ -81,7 +81,8 @@ class Page:
     
     @property
     def full_page_number(self):
-        return f"{self.magazine}{self.page_number:02d}"
+        # Format as Hex to support A-F pages
+        return f"{self.magazine}{self.page_number:02X}"
 
 @dataclass
 class TeletextService:

src/teletext/ui.py

@@ -496,7 +496,8 @@ class MainWindow(QMainWindow):
         sorted_keys = sorted(self.page_groups.keys())
         
         for mag, pnum in sorted_keys:
-            label = f"{mag}{pnum:02d}"
+            # Display as Hex
+            label = f"{mag}{pnum:02X}"
             item = QListWidgetItem(label)
             item.setData(Qt.ItemDataRole.UserRole, (mag, pnum))
             self.page_list.addItem(item)