Report question: skip a broken card and tell the server

A generated matching card arrived on a phone with three identical
definitions (the generation guards now drop those), but there was no way
to get past a bad card from inside a session. The feed chrome (deck
study, review, mistakes and exam) now has the red "!" control: one tap
records the question, skips to the next card and shows an Undo toast.

- lib/question-reports.ts: the local list (freezmo.reports.v1, zod on
  read, capped 200) is the skip state — reported cards leave every
  session type, count as "not attempted" in the results instead of
  wrong, and Undo takes a report back. A deck where everything is
  reported stays studiable so it can be regenerated.
- POST /api/reports appends one JSON line per report to
  REPORTS_DIR/reports.jsonl (shared/freezmo/reports in production, the
  dev data dir in dev). Deliberately write-only: the question text is
  readable on the server (that is the point — prompt tuning) but never
  over HTTP, since the app has no auth. Best effort: offline reports stay
  local.
- The button: a red outlined rounded square with "!", the chrome's
  control size, in both feed headers (hidden on the results slide).
- config: REPORTS_DIR + RATE_LIMIT_REPORTS (20); the deploy creates the
  shared reports dir; the dev unit and AGENTS.md note the new server
  data location.
- Suites: phase-1 (append + validation + no GET), phase-2 (button, toast,
  server POST, local copy, skip counter, hidden next session, Undo, exam
  pool). SW -> freezmo-v38.

components/SessionFeed.tsx

@@ -4,6 +4,7 @@ import { useCallback, useEffect, useRef, useState } from "react";
 
 import { ActivityRenderer } from "@/components/activities";
 import { XIcon } from "@/components/icons";
+import { ReportQuestionButton } from "@/components/ReportQuestionButton";
 import { ProgressBar } from "@/components/ui";
 import type { Activity, Deck } from "@/lib/schemas";
 import { useI18n } from "@/lib/i18n";
@@ -48,6 +49,8 @@ export function SessionFeed({
   useWakeLock(true);
   const [index, setIndex] = useState(0);
   const [results, setResults] = useState<Record<string, SessionResult>>({});
+  /** Ids reported during this run: skipped, so they are not "missed". */
+  const [skipped, setSkipped] = useState<string[]>([]);
   const [runId] = useState(0);
   const [remaining, setRemaining] = useState(timerSeconds ?? 0);
   const scrollRef = useRef<HTMLDivElement>(null);
@@ -135,7 +138,9 @@ export function SessionFeed({
 
   const finished = index >= total;
   const correct = items.filter((item) => results[item.activity.id]?.correct).length;
-  const score = total > 0 ? Math.round((correct / total) * 100) : 0;
+  /** What the results slide counts: reported cards were never attempted. */
+  const attemptedTotal = Math.max(0, total - skipped.length);
+  const score = attemptedTotal > 0 ? Math.round((correct / attemptedTotal) * 100) : 0;
 
   return (
     <div className="frost-bg fixed inset-0 flex flex-col fade-in-mobile">
@@ -168,6 +173,16 @@ export function SessionFeed({
                 {formatClock(remaining)}
               </span>
             ) : null}
+            {!finished && items[index] ? (
+              <ReportQuestionButton
+                deck={items[index].deck}
+                activity={items[index].activity}
+                onSkip={() => {
+                  setSkipped((current) => [...current, items[index].activity.id]);
+                  goTo(index + 1);
+                }}
+              />
+            ) : null}
           </div>
           <div className="flex items-center justify-between gap-2 text-[11px] font-semibold text-[var(--text-muted)]">
             <span className="min-w-0 truncate">{title}</span>
@@ -211,7 +226,7 @@ export function SessionFeed({
         >
           <div className="mx-auto flex min-h-full w-full max-w-xl flex-col gap-4 px-4 pb-24 pt-24 [justify-content:safe_center]">
             {finished
-              ? renderResults({ results, items, correct, total, score })
+              ? renderResults({ results, items, correct, total: attemptedTotal, score })
               : (
                 <div className="card space-y-2 p-5 text-center">
                   <p className="text-sm font-semibold text-[var(--text-muted)]">{t("review.results")}</p>