Address follow-up review: cheaper avatars, list limits, less chatter.

Switch avatar resize to ApproxBiLinear, cap hunt/profile/admin list queries, drop redundant admin/profile lookups, dedupe CI on app PRs, and refresh stale todo.md notes.

internal/store/memory.go

@@ -92,6 +92,9 @@ func (m *Memory) ListUsers(_ context.Context) ([]User, error) {
 		out = append(out, *u)
 	}
 	sort.Slice(out, func(i, j int) bool { return out[i].CreatedAt < out[j].CreatedAt })
+	if len(out) > AdminUsersLimit {
+		out = out[:AdminUsersLimit]
+	}
 	return out, nil
 }
 
@@ -223,6 +226,9 @@ func (m *Memory) ListHunt(_ context.Context, huntDate, viewerID string) ([]Ranke
 		}
 		return out[i].CreatedAt < out[j].CreatedAt
 	})
+	if len(out) > HuntListLimit {
+		out = out[:HuntListLimit]
+	}
 	return out, nil
 }
 
@@ -237,6 +243,9 @@ func (m *Memory) ListQuestionsByAuthor(_ context.Context, authorID string) ([]Ra
 		out = append(out, m.annotate(q, ""))
 	}
 	sort.Slice(out, func(i, j int) bool { return out[i].CreatedAt > out[j].CreatedAt })
+	if len(out) > ProfileListLimit {
+		out = out[:ProfileListLimit]
+	}
 	return out, nil
 }
 
@@ -257,6 +266,9 @@ func (m *Memory) ListQuestionsAnsweredBy(_ context.Context, adminID string) ([]R
 		out = append(out, rq)
 	}
 	sort.Slice(out, func(i, j int) bool { return out[i].CreatedAt > out[j].CreatedAt })
+	if len(out) > ProfileListLimit {
+		out = out[:ProfileListLimit]
+	}
 	return out, nil
 }