fix(voice): stop reading a dictated jaw as a broken tooth

"یه کامپلیت دنچر برای فک بالا میخوام" resolved the upper arch and the
complete denture correctly, but the review sheet also showed
position_out_of_range against «فک بالا» and asked which tooth was meant. No
tooth was said.

The model names the jaw in the top-level `teeth` array as well as in the
prosthesis target it belongs to. resolveVoiceIntent passed that array
straight to resolveToothIntents, extraction.wire.ts turns `position: null`
into NaN, and unresolvedReason tests positionBad first — so it reported a
range fault for a value that was never a number, before ever reaching the
quadrant branch.

resolveVoiceIntent now drops jaw-shaped entries — an arch with no usable
position — before the tooth resolver sees them. The jaw already reaches the
form through its assignment, so the duplicate carries no information worth
reporting. An entry that DOES give a position survives: arch plus position
without a side is a real tooth described without its quadrant, and must keep
offering its candidate chips.

Two invitations removed as well, both ours: the `teeth` property in
VOICE_INTENT_JSON_SCHEMA had no description at all, and no prompt rule said a
jaw must stay out of it, while TOOTH_SCHEMA — shared with
prosthesis[].targets — describes jaws as acceptable. Adds the description and
HARD RULE 6.

Four tests. The two jaw cases fail without the filter; the out-of-range and
missing-quadrant cases pass either way and exist to prove the filter does not
over-reach.

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

backend/src/modules/voice/extraction.wire.ts

@@ -135,7 +135,13 @@ export const VOICE_INTENT_JSON_SCHEMA = {
       type: ['string', 'null'],
       description: 'A treatment type CODE from the supplied list, or null.',
     },
-    teeth: { type: 'array', items: TOOTH_SCHEMA },
+    teeth: {
+      type: 'array',
+      description:
+        'Individual teeth only. A whole jaw NEVER belongs here — put it in ' +
+        'prosthesis[].targets with "arch" set and "position" null.',
+      items: TOOTH_SCHEMA,
+    },
     connectedSpans: {
       type: 'array',
       description: 'Bridges / splinted units. Endpoints inclusive.',