Display printable tape width

app/app.py

@@ -444,6 +444,13 @@ def media_type_from_output(output: str) -> dict[str, str] | None:
     }
 
 
+def printable_width_from_output(output: str) -> int | None:
+    match = re.search(r"maximum printing width[^\n]*?(\d+)\s*px", output, re.IGNORECASE)
+    if not match:
+        return None
+    return int(match.group(1))
+
+
 def detect_tape_info() -> dict[str, Any]:
     result = subprocess.run(
         ["ptouch-print", "--info"],
@@ -472,6 +479,7 @@ def detect_tape_info() -> dict[str, Any]:
 
     return {
         "width": width,
+        "printableWidthPx": printable_width_from_output(output),
         "mediaType": media_type_from_output(output),
         "tapeColor": color_info_from_line(output, "tape color"),
         "textColor": color_info_from_line(output, "text color"),