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.spec.ts

@@ -150,6 +150,57 @@ describe('resolveToothIntents', () => {
     }
   });
 
+  it('says the quadrant is missing rather than blaming the words', () => {
+    // Regression: "ترمیم برای دندون دو" reported "could not be read", sending the
+    // clinician to look for a transcription fault. Position 2 was understood fine —
+    // what is missing is the quadrant, and four teeth carry position 2.
+    const bare = {
+      kind: 'positional',
+      arch: null,
+      side: null,
+      position: 2,
+      spoken: 'دندون دو',
+    } as unknown as ToothIntent;
+
+    const result = resolveToothIntents([bare]);
+    expect(result.teeth).toEqual([]);
+    expect(result.unresolved).toEqual([
+      { spoken: 'دندون دو', reason: 'tooth_missing_quadrant' },
+    ]);
+  });
+
+  it('reports a missing quadrant for a half-specified tooth too', () => {
+    // "دو بالا" narrows it to 12 or 22 — still not one tooth, and still not our guess.
+    for (const half of [
+      { arch: 'upper', side: null },
+      { arch: null, side: 'patient_right' },
+    ]) {
+      const result = resolveToothIntents([
+        {
+          kind: 'positional',
+          ...half,
+          position: 2,
+          spoken: 'دو',
+        } as unknown as ToothIntent,
+      ]);
+      expect(result.unresolved[0].reason).toBe('tooth_missing_quadrant');
+    }
+  });
+
+  it('still calls an out-of-range position out of range when the quadrant is missing', () => {
+    // Position wins: "nine" is wrong however completely it was said.
+    const result = resolveToothIntents([
+      {
+        kind: 'positional',
+        arch: null,
+        side: null,
+        position: 9,
+        spoken: 'نه',
+      } as unknown as ToothIntent,
+    ]);
+    expect(result.unresolved[0].reason).toBe('position_out_of_range');
+  });
+
   it('keeps unresolved items separate when the model omits the spoken span', () => {
     // Without `spoken` these are indistinguishable; collapsing them would hide a lost tooth.
     const result = resolveToothIntents([