fix: address remaining minor code review findings (FAR-15)

- #9: match Paperclip container by name in k8s-client instead of
  trusting spec.containers[0], which could be a service-mesh sidecar
- #11: key assistant-text dedup by (message.id, index) so legitimate
  duplicate content across turns isn't collapsed in the summary
- #16: trim trailing hyphens from sanitized K8s names so truncation
  doesn't produce names ending in "-"

Findings #5 (keepalive re-verify) and #6 (one-shot log dedup) were
already addressed in the current code — verified during this review.
#8 (orphan reattach behavior) requires a product decision on whether
"new session wins" is intentional, so deferring.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/server/job-manifest.ts

@@ -203,7 +203,9 @@ export interface JobBuildResult {
 }
 
 function sanitizeForK8sName(value: string, maxLen = 16): string {
-  return value.toLowerCase().replace(/[^a-z0-9-]/g, "").slice(0, maxLen);
+  // Trim trailing hyphens after slicing so names don't end with `-` when
+  // truncation lands on a hyphen boundary (finding #16, FAR-15).
+  return value.toLowerCase().replace(/[^a-z0-9-]/g, "").slice(0, maxLen).replace(/-+$/, "");
 }
 
 /**