fix(models): normalize trailing @profile parsing across resolver paths

Co-authored-by: Vincent Koc <vincentkoc@ieee.org>
Co-authored-by: Marcus Castro <mcaxtr@gmail.com>
Co-authored-by: Brandon Wise <brandonawise@gmail.com>

src/agents/model-ref-profile.ts

@@ -0,0 +1,23 @@
+export function splitTrailingAuthProfile(raw: string): {
+  model: string;
+  profile?: string;
+} {
+  const trimmed = raw.trim();
+  if (!trimmed) {
+    return { model: "" };
+  }
+
+  const profileDelimiter = trimmed.lastIndexOf("@");
+  const lastSlash = trimmed.lastIndexOf("/");
+  if (profileDelimiter <= 0 || profileDelimiter <= lastSlash) {
+    return { model: trimmed };
+  }
+
+  const model = trimmed.slice(0, profileDelimiter).trim();
+  const profile = trimmed.slice(profileDelimiter + 1).trim();
+  if (!model || !profile) {
+    return { model: trimmed };
+  }
+
+  return { model, profile };
+}