Let reviews see low-confidence suggestions and rebase preview applies

A low-confidence answer was discarded inside Classify, so Analyse showed
the row as unchanged instead of a reviewable suggestion; the fallback
decision moves to the import path, which keeps the merchant link and the
recorded confidence. ApplyPreview now rebases onto the current journal:
unrelated commits during a minutes-long paced run no longer invalidate
the review, only an edit to a selected transaction itself conflicts, and
applied changes are pruned so the rest stay appliable.

web/src/Classification.tsx

@@ -359,9 +359,10 @@ export function Classification({
             </span>
           </div>
           {preview.revision !== state.revision && (
-            <div className="alert error">
-              Your journal changed since this preview. Cancel it and generate a
-              fresh preview before applying.
+            <div className="alert">
+              Your journal changed since this preview. Selected changes still
+              apply as long as their transactions were not edited in the
+              meantime.
             </div>
           )}
           <section className="panel">
@@ -449,11 +450,7 @@ export function Classification({
               </button>
               <button
                 className="button primary"
-                disabled={
-                  busy ||
-                  !selected.length ||
-                  preview.revision !== state.revision
-                }
+                disabled={busy || !selected.length}
                 onClick={() => setConfirm(true)}
               >
                 <Check size={16} />
@@ -506,7 +503,7 @@ export function Classification({
             </button>
             <button
               className="button primary"
-              disabled={busy || preview.revision !== state.revision}
+              disabled={busy}
               onClick={async () => {
                 setBusy(true);
                 setError("");
@@ -520,7 +517,14 @@ export function Classification({
                     result,
                     `Applied ${selected.length} classifications`,
                   );
-                  setPreview(null);
+                  const remaining = preview.changes.filter(
+                    (c) => !selected.includes(c.id),
+                  );
+                  setPreview(
+                    remaining.length
+                      ? { ...preview, changes: remaining }
+                      : null,
+                  );
                   setSelected([]);
                   setConfirm(false);
                 } catch (err) {