fix(forms): send one Idempotency-Key per opened create form

A mood, symptom, lab value, custom metric value, unscheduled dose,
allergy, vaccination, visit or measurement saved on a weak signal could
be stored twice: the POST committed, the answer missed the 15 s
timeout, the form said it could not save, and the second tap was a new
call with a new key, so the server ran it again.

useIdempotentPost keeps one key until a save lands and renews it for the
next entry, so the retry replays the first answer. The create forms and
the three create hooks post through it; the comment on the per-call key
in api-fetch now says what that key does and does not cover.

LabForm and MoodForm each gain the one line that mounts the key, so
their function-size baselines go up by one. The intake toast guard now
recognises a dose posted through the hook.

src/__tests__/baselines/source-function-lines.json

@@ -134,7 +134,7 @@
     "components/labs/biomarker-merge-sheet.tsx :: BiomarkerMergeSheet": 239,
     "components/labs/lab-biomarker-chart.tsx :: LabBiomarkerChart": 370,
     "components/labs/lab-biomarker-detail.tsx :: LabBiomarkerDetail": 481,
-    "components/labs/lab-form.tsx :: LabForm": 473,
+    "components/labs/lab-form.tsx :: LabForm": 474,
     "components/labs/lab-history-list.tsx :: LabHistoryList": 534,
     "components/labs/ocr-review-dialog.tsx :: OcrReviewDialog": 359,
     "components/labs/ocr-row-editor.tsx :: OcrRowEditor": 378,
@@ -173,7 +173,7 @@
     "components/mental-health/mental-wellbeing.tsx :: MentalWellbeing": 202,
     "components/mood/manage/tag-groups-card.tsx :: TagGroupsCard": 256,
     "components/mood/manage/tag-manager-card.tsx :: TagManagerCard": 270,
-    "components/mood/mood-form.tsx :: MoodForm": 513,
+    "components/mood/mood-form.tsx :: MoodForm": 514,
     "components/mood/mood-list.tsx :: MoodList": 1109,
     "components/mood/mood-tag-picker.tsx :: MoodTagPicker": 257,
     "components/onboarding/confirm-screen.tsx :: ConfirmScreen": 255,

src/__tests__/intake-toast-single-decision.test.ts

@@ -111,12 +111,31 @@ export function intakeFacts(source: string, fileName: string): IntakeFacts {
     callsHelper: false,
   };
 
+  // A create form posts through the function `useIdempotentPost()` returns
+  // (one key per opened form), bound to a local name.
+  const posters = new Set<string>();
+  const findPosters = (node: ts.Node): void => {
+    if (
+      ts.isVariableDeclaration(node) &&
+      ts.isIdentifier(node.name) &&
+      node.initializer &&
+      ts.isCallExpression(node.initializer) &&
+      ts.isIdentifier(node.initializer.expression) &&
+      (aliases.get(node.initializer.expression.text) ??
+        node.initializer.expression.text) === "useIdempotentPost"
+    ) {
+      posters.add(node.name.text);
+    }
+    node.forEachChild(findPosters);
+  };
+  parsed.forEachChild(findPosters);
+
   const visit = (node: ts.Node): void => {
     if (ts.isCallExpression(node)) {
       const callee = node.expression;
       if (ts.isIdentifier(callee)) {
         const name = aliases.get(callee.text) ?? callee.text;
-        if (name === "apiPost") {
+        if (name === "apiPost" || posters.has(callee.text)) {
           const url = urlText(node);
           if (url !== null && url.endsWith("/intake")) facts.postsIntake = true;
         }