Harden quick-add against review findings

Independent review of the quick-add range surfaced real holes:

- The emptyLabel guard suppressed creation for any name that happened
  to be a substring of the label — typing "Rent" in the parent picker
  (a substring of "No parent (root)") silently offered nothing. The
  guard is gone; the exact-match rule already suppresses creates when
  the full label is typed.
- Async creates resolved against click-time snapshots, so a checkbox
  toggled or chip removed during the server round trip was silently
  reverted. Consumers now apply functional updates or a latest-value
  ref.
- Created names are capped at 200 characters, matching the registry
  forms; over-long text fails inline instead of minting a permanent
  multi-kilobyte name.
- A create failing after the user blurred mid-flight reopens the list
  so the error is never invisible, and option rows are locked while a
  create is in flight so a race cannot override an explicit pick.

web/src/Classification.tsx

@@ -695,6 +695,11 @@ function CorrectionEditor({
   mutate: Mutate;
   onChange: (value: CorrectionValue) => void;
 }) {
+  // Async creates resolve against the freshest correction, not the snapshot
+  // captured when the create row was clicked: a chip removed during the
+  // server round trip must survive the create landing.
+  const latest = useRef(value);
+  latest.current = value;
   const addable = data.tags
     .filter((t) => !value.tag_ids.includes(t.id))
     .map((t) => ({ value: t.id, label: t.name }));
@@ -739,7 +744,9 @@ function CorrectionEditor({
               mutate={mutate}
               value={value.category_id}
               disabled={disabled}
-              onChange={(category_id) => onChange({ ...value, category_id })}
+              onChange={(category_id) =>
+                onChange({ ...latest.current, category_id })
+              }
             />
           </dd>
         </div>
@@ -783,14 +790,13 @@ function CorrectionEditor({
                         {
                           key: "tag",
                           label: `Create tag "${text}"`,
-                          run: async () =>
+                          run: async () => {
+                            const id = await createTag(mutate, data, text);
                             onChange({
-                              ...value,
-                              tag_ids: [
-                                ...value.tag_ids,
-                                await createTag(mutate, data, text),
-                              ],
-                            }),
+                              ...latest.current,
+                              tag_ids: [...latest.current.tag_ids, id],
+                            });
+                          },
                         },
                       ]
                 }