fix(api): enforce range and source guards on the measurement edit path

PUT /api/measurements/[id] was the one write surface that skipped the
per-type plausibility bands — POST, batch, CSV import, Apple export,
Telegram and MCP all enforce VALUE_RANGES — so an implausible edited
value flowed unchecked into rollups, the health score, the BP gates
and the Coach snapshot. The route now validates the new value against
the row's own type after the lookup and returns the standard
multi-issue 422 envelope on violation.

Value edits on server-owned sources (anything outside
WRITABLE_MEASUREMENT_SOURCES: connector, import, computed rows) are
refused with 409 and the stable errorCode
measurement.update.server_owned_source — editing a provider-attributed
number forges a reading the server never received. Timestamp and note
edits stay allowed, and the edit sheet shows a localised message for
the new code.

The schema's generic min(0).max(500000) bound is dropped: the per-type
band is stricter where it matters, and min(0) blocked legitimate edits
of the signed types (ANS_CHARGE, BODY_TEMPERATURE_DEVIATION). Route
tests cover out-of-range 422, negative signed-type accept, the
server-owned 409, a timestamp-only edit on a server-owned row, and the
happy path. The PUT endpoint is not part of the published OpenAPI
surface — the generated contract is unchanged.

src/components/measurements/measurement-list.tsx

@@ -654,6 +654,15 @@ export function MeasurementList({
         setEditError(t("measurements.duplicateTimestamp"));
         return;
       }
+      // v1.27.5 (di-001) — value edits on server-owned sources
+      // (connector / import / computed rows) are refused with a 409.
+      if (
+        err instanceof ApiError &&
+        err.meta?.errorCode === "measurement.update.server_owned_source"
+      ) {
+        setEditError(t("measurements.serverOwnedSource"));
+        return;
+      }
       setEditError(
         err instanceof Error ? err.message : t("measurements.saveError"),
       );