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,