A05: Add sessionStorage error handling for unavailable storage

Bug: sessionStorage operations (getItem, setItem, removeItem) could fail
if storage is unavailable (private mode, quota exceeded, etc.), causing
form draft recovery to break.

Fix: Wrap all sessionStorage operations in try/catch via safeStorage helper.
- safeStorage.getItem() - returns null on error
- safeStorage.setItem() - silently ignores errors
- safeStorage.removeItem() - silently ignores errors

This ensures:
- Draft recovery works even if storage is partially unavailable
- Form submission doesn't crash if storage is full
- Cleanup on success doesn't crash
- File input values are not saved (already handled by FormData filter)

Verification:
- Astro build: 0 errors
- All existing A05 behavior preserved
- Error handling added for read, write, and cleanup

apps/web/src/pages/report.astro

@@ -22,11 +22,17 @@ const reportId = Astro.url.searchParams.get("report_id");
   </form>}
   <script is:inline define:vars={{ state }}>
     const form = document.querySelector(".report-form"); const key = "rf4-report-draft";
+    // A05: Safe sessionStorage access with error handling
+    const safeStorage = {
+      getItem: (k) => { try { return sessionStorage.getItem(k); } catch { return null; } },
+      setItem: (k, v) => { try { sessionStorage.setItem(k, v); } catch {} },
+      removeItem: (k) => { try { sessionStorage.removeItem(k); } catch {} },
+    };
     // A05: Restore draft on all error states that don't destroy the submission
     const recoverableStates = ["create_error", "rate_limited", "server_error", "timeout"];
     if (form && recoverableStates.includes(state)) {
       try {
-        const draft = JSON.parse(sessionStorage.getItem(key) || "{}");
+        const draft = JSON.parse(safeStorage.getItem(key) || "{}");
         for (const [name, value] of Object.entries(draft)) {
           const field = form.elements.namedItem(name);
           if (field && "value" in field) field.value = value;
@@ -34,12 +40,18 @@ const reportId = Astro.url.searchParams.get("report_id");
       } catch {}
       document.querySelector("#form-error")?.focus();
     }
-    if (state === "sent" || state === "screenshot_sent") sessionStorage.removeItem(key);
+    if (state === "sent" || state === "screenshot_sent") safeStorage.removeItem(key);
     form?.addEventListener("submit", () => {
       const btn = form.querySelector("button[type=submit]");
       if (btn) { btn.disabled = true; btn.textContent = "Отправка..."; }
-      const draft = {}; for (const [name, value] of new FormData(form)) if (typeof value === "string" && name !== "website") draft[name] = value;
+      // A05: Save draft before submit, handle sessionStorage unavailable
-      sessionStorage.setItem(key, JSON.stringify(draft));
+      const draft = {};
+      try {
+        for (const [name, value] of new FormData(form)) {
+          if (typeof value === "string" && name !== "website") draft[name] = value;
+        }
+        safeStorage.setItem(key, JSON.stringify(draft));
+      } catch {}
     });
   </script>
 </Layout>