docs(sharing): the booster needs two sections, and the guide promised it at one level

The write-level row listed "a vaccination dose and the booster reminder it
suggests" three paragraphs under a section table that puts the vaccination
record in Health background. Read together, that tells a self-hoster a
health-background WRITE grant can plan a booster — which the route beside it
now refuses, because the reminder it mints lives under Readings. The row lists
the dose alone, and the exceptions paragraph, which is where a reader looks for
exactly this, carries the two-section case and says the dose logs either way.

With it, the small things the same pass turned up:

The cycle-insights fixture asserted a property it could not show. Its docblock
claims the cycle-native answer survives the fence, and it seeded no symptom at
all, so `symptomPatterns` was empty in every leg and a regression that emptied
it along with the foreign columns would have passed green. One catalogue
symptom on the luteal days, asserted on the owner leg and on the cycle-only
one.

The immunization rows matched on a bare `role="button"`, which passes vacuously
the day the card becomes a real button and fails for the wrong reason if
anything else in the subtree grows one. They carry the same stable marker the
visit card took.

`/api/cycle/calendar` reads the same wrist-temperature channel the crosstab
does and is deliberately not fenced, and it was the only one of the pair with
nothing saying why: no value from it reaches the response.

The encrypted export's new 403 documented the switch refusal and not the
narrow-scope one it answers first, unlike the two settings operations beside
it. Both sheets say at the top that their Save and Delete are gated at the
caller, so a third mount reads the constraint before it violates it. And one
docblock line ran past the wrap.

src/app/api/cycle/calendar/route.ts

@@ -111,6 +111,12 @@ export const GET = apiHandler(async (request: NextRequest) => {
     // Apple Watch wrist/skin temperature feeds the temperature-trend
     // ovulation layer. Read the WRIST_TEMPERATURE measurements as nightly
     // values; the engine derives the trailing-mean deviation itself.
+    //
+    // This is a measurements read on a route declared under `cycle`, and it
+    // needs no section predicate for one reason: no value from it reaches the
+    // response. It goes into `predictCycle` and what comes out the other side
+    // is a shifted date. The crosstab next door reads the same channel and IS
+    // fenced, because there the values are the answer.
     prisma.measurement.findMany({
       where: {
         userId: user.id,