feat: wire voice entry into the treatment workspace

Makes the feature reachable end to end: availability is fetched alongside the
catalogs, the capture hook drives the segmented control, and confirming the
review sheet appends a new detail.

Confirm always appends — it never edits an existing detail and never calls
onAddDetail. Ticked rows land on top of the seeded defaults, so unticking the
type row leaves the appointment-purpose default rather than a blank. Lab-side
rows ride on a lab case draft keyed by the detail's *client* id, so a brand-new
unsaved detail can carry a lab, due date and per-tooth prosthesis map.

Availability comes from the API rather than a NEXT_PUBLIC_* var, since those are
baked in at build time; a failure fetching it degrades to no microphone rather
than taking the treatment tab down.

From review of this commit:

- Unticking "teeth" while leaving "prosthesis" ticked attached prosthesis rows
  for teeth the detail does not contain. Nothing downstream filters them —
  assertCompleteToothProsthesisMap only checks detail-teeth ⊆ map, never the
  reverse — so they would have reached task generation as lab work for teeth
  nobody is treating. The map is now filtered to the detail's own teeth.
- The microphone was gated on the URL locale while the server resolved
  everything from req.user.language. Those diverge (a bookmarked /fa/ URL, a
  language toggle whose save failed), which would transcribe Persian with an
  English hint and anchor "next Thursday" to a Monday week instead of a Saturday
  one — or 403 from a visibly-enabled button. The client now sends the locale the
  microphone was offered in, so the gate and the request agree by construction.

Also fixed from the previous review: a civil YYYY-MM-DD date rendered a day
early west of Greenwich (parsed as UTC midnight); the missing-teeth list
hardcoded the Arabic comma for all locales; and voiceApply had no ICU plural, so
the common single-field case read "Apply 1 fields".

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

frontend/messages/nl.json

@@ -903,7 +903,24 @@
     "voiceStart": "Behandeling inspreken",
     "voiceStop": "Opname stoppen",
     "voiceCancel": "Annuleren",
-    "voiceProcessing": "Opname wordt gelezen…"
+    "voiceProcessing": "Opname wordt gelezen…",
+    "voiceReviewTitle": "Controleer wat is begrepen",
+    "voiceNothingExtracted": "Uit deze opname is niets bruikbaars opgepikt.",
+    "voiceProsthesisIncomplete": "Geen prothesetype voor {teeth} — de casus kan pas worden verstuurd als elk element er een heeft.",
+    "voiceLabInexact": "De uitgesproken naam kwam slechts deels overeen met dit lab. Bevestig voor verzending.",
+    "voiceNotUnderstood": "Niet begrepen",
+    "voiceDiscard": "Verwerpen",
+    "voiceApply": "{count, plural, one {# veld toepassen} other {# velden toepassen}}",
+    "voiceUnresolved": {
+      "not_permanent_tooth": "geen blijvend element",
+      "position_out_of_range": "geen geldige elementpositie",
+      "malformed": "kon niet worden gelezen",
+      "span_not_same_arch": "een brug kan niet over beide kaken lopen",
+      "unknown_catalog_code": "staat niet in de lijst van deze praktijk",
+      "tooth_not_selected": "dat element hoort niet bij dit onderdeel",
+      "invalid_date": "geen bruikbare datum"
+    },
+    "voiceFailed": "Spraakinvoer is mislukt. Probeer het opnieuw."
   },
   "organizations": {
     "loadingOrganization": "Organisatie laden...",