fix(ui): strip trailing dashes in slugify (#1387)

slugify's docstring promises "no leading/trailing dashes" and the sibling
isValidSlug rejects a trailing dash, but slugify only stripped leading
dashes. Any input ending in a non-[a-z0-9] character (e.g. "hello world!",
a trailing space, "trailing---") produced a slug ending in "-" that then
failed isValidSlug, causing invalid persisted keys and spurious validation
errors on agent/channel/provider/cron/mcp name fields. Add a symmetric
trailing-dash strip, matching the Go helpers (strings.Trim(s, "-")).

ui/web/src/lib/slug.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+
+import { isValidSlug, slugify } from "./slug";
+
+describe("slugify", () => {
+  it("does not leave a trailing dash and passes isValidSlug", () => {
+    for (const input of ["hello world!", "My Agent ", "trailing---", "café résumé!", "  spaced  "]) {
+      const s = slugify(input);
+      expect(s.endsWith("-")).toBe(false);
+      expect(isValidSlug(s)).toBe(true);
+    }
+    expect(slugify("hello world!")).toBe("hello-world");
+  });
+
+  it("still handles already-valid slugs and diacritics", () => {
+    expect(slugify("valid-slug")).toBe("valid-slug");
+    expect(slugify("abc")).toBe("abc");
+    expect(slugify("Đà Nẵng")).toBe("da-nang");
+  });
+});

ui/web/src/lib/slug.ts

@@ -11,7 +11,8 @@ export function slugify(input: string): string {
     .toLowerCase()
     .replace(/[^a-z0-9-]/g, "-")
     .replace(/-{2,}/g, "-")
-    .replace(/^-+/g, "");
+    .replace(/^-+/g, "")
+    .replace(/-+$/g, "");
 }
 
 /**