feat(filters): JSONPath field filters, operators, AST groups, fragments, and test-match

Add a field filter type reading any payload value by JSONPath with array expansion, 12 comparison operators (eq/ne/contains/startsWith/endsWith/regex/gt/gte/lt/lte/in/exists), a visual AST builder (all/any/not) in the route editor, chip-based multi-value input, a stateless POST /admin/api/test-match dry-run, and named filter fragments stored in D1 (d1_fragments, migration 0010) inlined into route ASTs on insert.

app/composables/useFragments.ts

@@ -0,0 +1,34 @@
+import type { NamedFragment } from "~/types";
+
+export function useFragmentsApi() {
+  const { needLogin } = useAuthState();
+  const fragments = ref<NamedFragment[]>([]);
+  const loading = ref(false);
+  const error = ref("");
+
+  async function load(groupId: string): Promise<void> {
+    loading.value = true;
+    error.value = "";
+    needLogin.value = false;
+    try {
+      const data = await apiFetch<{ fragments?: NamedFragment[] }>(
+        `/admin/api/groups/${encodeURIComponent(groupId)}/fragments`,
+      );
+      fragments.value = data.fragments ?? [];
+    } catch (err) {
+      if (!needLogin.value) error.value = err instanceof Error ? err.message : String(err);
+    } finally {
+      loading.value = false;
+    }
+  }
+
+  async function save(groupId: string, next: NamedFragment[]): Promise<void> {
+    await apiFetch(`/admin/api/groups/${encodeURIComponent(groupId)}/fragments`, {
+      method: "PUT",
+      body: JSON.stringify({ fragments: next }),
+    });
+    fragments.value = next;
+  }
+
+  return { fragments, loading, needLogin, error, load, save };
+}