Function similarity

src/dashboard/memory_api.rs:371–381

`GET /api/plugins/holographic/similarity` — pairwise phase-cosine similarity (`mean(cos(p_i − p_j))`) over all vectored facts. `min_similarity` is the single floor parameter; the response still emits the same value under both the `min_similarity` and legacy `threshold` keys so the payload shape is unchanged.

(
    State(state): State<DashboardState>,
    JsonQuery(params): JsonQuery<SimilarityParams>,
)

/// the same value under both the `min_similarity` and legacy `threshold`
/// keys so the payload shape is unchanged.
pub(crate) async fn similarity(
    State(state): State<DashboardState>,
    JsonQuery(params): JsonQuery<SimilarityParams>,
) -> Json<Value> {
    let min_similarity = memory_service::coerce_similarity_score(
        params.min_similarity,
        SIMILARITY_DEFAULT_THRESHOLD,
    );
    let pair_cap = coerce_limit(params.limit, 25, SIMILARITY_PAIR_CAP) as usize;
    Json(memory_service::similarity_payload(&state, min_similarity, pair_cap).await)
}

/// `GET /api/plugins/holographic/curation/status` — similarity-dedup curator status.
pub(crate) async fn curation_status(State(state): State<DashboardState>) -> Json<Value> {