docs: cut the comments that were not earning their place

I wrote 731 comment lines on this branch against 4,530 lines of code — 14%,
where the rest of the repo runs at 1.8%. CLAUDE.md asks for code that reads
like its surroundings, and this did not.

Removed by genre rather than by taste:

- restating the code, e.g. "JS getUTCDay() numbering: Sunday = 0" above the
  map that literally shows it, and a docblock on startOfWeek explaining that
  it returns the start of the week;
- narrating history — "this used to rebuild the whole map", "left the bar
  recording forever" — which the commit message and git blame already carry;
- saying the same thing in several places: the "cannot record is not a
  denied microphone" reason appeared three times in one file, and the
  "aborting stops a per-minute metered call" reason across three files. Each
  now lives once, where the behaviour it explains lives;
- defending decisions nobody would question, like why toLatinDigits is its
  own module;
- over-explaining defensive branches, three separate comments to distinguish
  null from missing-kind from unrecognised-kind.

What stays is what the code cannot say: the patient-right convention in
toFdi, whose failure mode is a valid code for the wrong tooth; the
"this"-vs-"next" week anchoring; StrictMode re-arming mountedRef; Safari
accepting no mimeType hint; and the invariants whose violation already cost
a bug — the body parser's middleware ordering and the dispatch panel's
auto-fill rules.

Comments only. The diff contains no non-comment line.

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

frontend/src/components/ui/treatment/TreatmentDetailsEditor.tsx

@@ -338,17 +338,12 @@ function NotesField({
 /**
  * "Add detail", split into two segments with the microphone at the logical end.
  *
- * Built like the detail chip's trash affordance in this same file — an
- * `inline-flex items-stretch overflow-hidden rounded` wrapper holding two raw `<button>`s
- * divided by `border-s` — rather than two shared `Button`s, which each hardcode their own
- * rounding and would fight a segmented control.
+ * Built like the detail chip's trash affordance in this same file — a wrapper holding two
+ * raw `<button>`s divided by `border-s` — rather than two shared `Button`s, which hardcode
+ * their own rounding and would fight a segmented control. `border-s` puts the microphone
+ * visually right in en/nl and left in fa, on the same side as the chip's trash in both.
  *
- * `border-s` puts the microphone at the *logical* end: visually right in en/nl, visually
- * left in fa, on the same side as the chip's trash in both directions.
- *
- * The two halves share a wrapper and nothing else. Add keeps its exact existing
- * behaviour; the microphone is an independent action that creates nothing until the
- * clinician confirms.
+ * Add keeps its exact existing behaviour; the microphone is an independent action.
  */
 function AddDetailWithVoice({
   addLabel,

frontend/src/components/ui/treatment/TreatmentWorkspace.tsx

@@ -2000,8 +2000,7 @@ export function TreatmentWorkspace({
 
       const nextDetails = [...detailsRef.current, detail];
       setDetails(nextDetails);
-      // persistDraft reads detailsRef, and setDetails has not rendered yet. The codebase
-      // already writes this ref imperatively after a save for the same reason.
+      // persistDraft reads detailsRef, and setDetails has not rendered yet.
       detailsRef.current = nextDetails;
       setActiveDetailId(detail.clientId);
       setEntryStep('treatment');
@@ -2045,19 +2044,16 @@ export function TreatmentWorkspace({
         const updatedLabCases = [...labCaseDrafts, draft];
         setLabCaseDrafts(updatedLabCases);
 
-        // Every other path that creates a lab draft persists it immediately, and the
-        // autosave effect only watches `details`. Left in state alone, the destination
-        // lab, the due date and the whole prosthesis map vanish on the next reload —
-        // silently, because the detail itself does survive.
+        // Autosave only watches `details`, so a lab draft left in state alone loses the
+        // lab, the due date and the prosthesis map on reload — silently, because the
+        // detail itself survives.
         void (async () => {
           try {
             const saved = await persistDraft({ force: true });
-            // persistDraft returns a *preview* treatment rather than saving when the
-            // details are not persistable — one blank detail, the kind the workspace opens
-            // with, is enough. A preview's detail id falls back to the client id, so
-            // posting lab cases against it would send the server an id it has never seen
-            // and fail the whole save. Check what came back, not the precondition, so this
-            // holds for every early return persistDraft has.
+            // persistDraft returns a *preview* when the details are not persistable — one
+            // blank detail is enough — and a preview's detail id falls back to the client
+            // id. Check what came back, not the precondition, so this holds for every early
+            // return persistDraft has.
             const savedDetail = saved.details.find((d) => d.clientId === detail.clientId);
             if (!savedDetail?.id || savedDetail.id === detail.clientId) return;
             await persistLabCases(saved, updatedLabCases);

frontend/src/components/ui/treatment/VoiceRecordingBar.tsx

@@ -16,9 +16,9 @@ function formatElapsed(ms: number): string {
 /**
  * Live recording / processing strip.
  *
- * Sits between the header row and the chip strip rather than inside the segmented
- * control: the header is `sm:justify-between`, so growing the button mid-recording would
- * shove the row on every start and every stop.
+ * Sits between the header row and the chip strip rather than inside the segmented control:
+ * the header is `sm:justify-between`, so growing the button mid-recording would shift the
+ * whole row.
  */
 export function VoiceRecordingBar({ voice }: { voice: VoiceCaptureState }) {
   const t = useTranslations('treatment');

frontend/src/components/ui/treatment/VoiceReviewSheet.tsx

@@ -38,9 +38,8 @@ interface VoiceReviewSheetProps {
 /**
  * Confirmation step between the model's output and the form.
  *
- * Modal on desktop, bottom sheet on mobile via ResponsiveDialog — deliberately an overlay
- * and not a route, because navigating would unmount TreatmentWorkspace and destroy the
- * in-progress draft.
+ * Modal on desktop, bottom sheet on mobile — an overlay and not a route, because navigating
+ * would unmount TreatmentWorkspace and destroy the in-progress draft.
  */
 export function VoiceReviewSheet({
   result,
@@ -78,10 +77,9 @@ export function VoiceReviewSheet({
       // The teeth row starts unticked whenever the recording produced no teeth of its own,
       // and a picked tooth that is not ticked applies nothing.
       teeth: true,
-      // The picked tooth has no prosthesis type, which makes the map unshippable. Leaving
-      // the row ticked would apply a map that `assertCompleteToothProsthesisMap` rejects
-      // at dispatch — the exact failure the never-auto-tick-incomplete rule exists to
-      // prevent. Only ever unticks: re-ticking is the clinician's call.
+      // A picked tooth has no prosthesis type, so the map is no longer shippable — leaving the
+      // row ticked would apply a map dispatch rejects. Only ever unticks; re-ticking is the
+      // clinician's call.
       prosthesis:
         prev.prosthesis &&
         withChosenTeeth(result, nextChosen).prosthesis?.complete !== false,
@@ -290,9 +288,8 @@ function Row({
 }
 
 /**
- * A bare `YYYY-MM-DD` is a *civil* date, but `new Date('2025-10-17')` parses it as UTC
- * midnight — which renders as the 16th for any viewer west of Greenwich. Build the date
- * from its parts so it means the same day everywhere.
+ * `new Date('2025-10-17')` parses a civil date as UTC midnight, which renders as the 16th
+ * west of Greenwich. Build it from its parts so it means the same day everywhere.
  */
 function civilDateToLocalDate(iso: string): Date {
   const [year, month, day] = iso.split('-').map(Number);