fix(voice): say the quadrant is missing instead of "could not be read"

"ترمیم برای دندون دو" set the treatment type but reported the tooth as
unreadable. Nothing was misheard: position 2 arrived intact, with no
quadrant, because none was spoken — four teeth carry position 2 and the
resolver correctly refused to pick one. Only the label was wrong, and it
sent the clinician looking for a transcription fault.

Adds a tooth_missing_quadrant reason that names what is missing and shows
how to say it ("دو بالا راست"), and tells the model explicitly to report a
quadrant-less number with arch and side null rather than guessing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

backend/src/modules/voice/tooth-intent.resolver.ts

@@ -55,7 +55,14 @@ function unresolvedReason(intent: ToothIntent): UnresolvedItem['reason'] {
       !Number.isInteger(intent.position) ||
       intent.position < 1 ||
       intent.position > 8;
-    return positionBad ? 'position_out_of_range' : 'malformed';
+    if (positionBad) return 'position_out_of_range';
+    // The position was understood, so the words were not the problem: the speaker never
+    // said which quadrant. "دندون دو" names four teeth at once, and telling the
+    // clinician it "could not be read" would send them looking for the wrong fault.
+    const archMissing = intent.arch !== 'upper' && intent.arch !== 'lower';
+    const sideMissing =
+      intent.side !== 'patient_right' && intent.side !== 'patient_left';
+    return archMissing || sideMissing ? 'tooth_missing_quadrant' : 'malformed';
   }
 
   return 'malformed';