fix(compiler): React Compiler safety triage — 5 categories cleared

Cleared 4 rule buckets (37 violations, including 5 real bugs) and
silenced 1 informational bucket from the Next 16 / react-hooks v7
upgrade. Cleared rules promoted from `warn` back to `error` so new
regressions block CI.

Real bug fixes:
- `interest-contact-log-tab.tsx`: `useMemo` used for side effects
  (5 setState calls inside a memo body); converted to `useEffect`.
- `PieChart.tsx`: cumulative `let angle` mutation in a render-phase
  `map`; converted to `reduce` so the slice array is built without
  re-assignment.
- `documents-hub.tsx`: `useMemo(() => ({ count: 0 }))` used as a
  mutable drag counter; converted to `useRef`.
- `notes-list.tsx`: `Date.now()` read during render for note-edit
  countdown (impure) → pinned to a `now` state ticked every 30s.
- `onboarding-checklist.tsx` / `user-profile.tsx` /
  `user-settings.tsx`: `useEffect(() => void load(), [])` with the
  `load` function declared AFTER the effect — relied on hoisting,
  trips Compiler's "access before declared" rule. Declared inside
  the effect.

Pattern fixes (intentional cache-via-ref → state or layout-effect):
- 6 `ref.current = x` writes during render moved into layout
  effects (`use-realtime-invalidation`, `settings-form-card`,
  `inbox`).
- 3 `ref.current` reads during render (search totals cache,
  scanner file ref) rewritten to backed-by-state.
- `use-is-mobile.ts` rewritten on `useSyncExternalStore` to avoid
  the SSR-then-rehydrate setState dance.
- `use-notifications.ts` rewritten to write socket pushes directly
  into the React Query cache via `setQueryData`, removing a local
  state mirror.

Rule config (`eslint.config.mjs`):
- `react-hooks/purity` → error (was warn, cleared)
- `react-hooks/set-state-in-render` → error (was warn, cleared)
- `react-hooks/immutability` → error (was warn, cleared)
- `react-hooks/refs` → error (was warn, cleared)
- `react-hooks/incompatible-library` → off (informational only)
- `react-hooks/set-state-in-effect` → warn (51 remaining, all the
  useEffect→fetch→setState data-fetch pattern; migration to
  useQuery tracked in BACKLOG)

Verified: tsc clean, eslint 0 errors / 69 warnings (down from 105),
vitest 1315/1315, next build green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/scan/scan-shell.tsx

@@ -328,6 +328,11 @@ export function ScanShell() {
   const fileRef = useRef<HTMLInputElement>(null);
   const [state, setState] = useState<ScanState>({ kind: 'idle' });
   const [imagePreview, setImagePreview] = useState<string | null>(null);
+  // Track the (possibly compressed) File alongside its preview URL.
+  // Reading fileRef.current.files[0] during render trips the React
+  // Compiler's ref-purity rule + would point at the *raw* uploaded
+  // bytes (pre-compression), not the resized bytes we OCR'd.
+  const [currentFile, setCurrentFile] = useState<File | null>(null);
 
   // Revoke blob URL on unmount.
   useEffect(() => {
@@ -345,6 +350,7 @@ export function ScanShell() {
     const file = await compressReceiptIfHeavy(rawFile);
     if (imagePreview) URL.revokeObjectURL(imagePreview);
     setImagePreview(URL.createObjectURL(file));
+    setCurrentFile(file);
     setState({ kind: 'processing', engine: 'tesseract' });
 
     // Always run Tesseract first - it's free, on-device, and gives us a
@@ -482,6 +488,7 @@ export function ScanShell() {
       URL.revokeObjectURL(imagePreview);
       setImagePreview(null);
     }
+    setCurrentFile(null);
     setState({ kind: 'idle' });
     if (fileRef.current) fileRef.current.value = '';
   }
@@ -563,7 +570,7 @@ export function ScanShell() {
         <VerifyForm
           parsed={state.parsed}
           imagePreview={imagePreview}
-          imageFile={fileRef.current?.files?.[0] as File}
+          imageFile={currentFile as File}
           source={state.source}
           reason={state.reason}
           providerError={state.providerError}