hive-c0re: remove dashboard peer-hives wiring (hyperhive#3294)

Removes the per-hive dashboard's "peer hives" display support:
`peer_hives` field on StateSnapshot, the `PeerHiveView` struct,
`parse_peer_hives()`, and `validate_cert_fingerprint()`. That surface
moved to swarm-ui's own hive roster page — no longer needed at the
hive level.

HYPERHIVE_PEERS itself is untouched: hive-agent::identity::peers()
still reads it for qualified agent labels, and the nix module still
forwards it to agent containers. Only this crate's dashboard-only
consumption is gone.

Verified: cargo build/clippy/test -p hive-c0re clean, grepped the
whole tree for stray peer_hives/PeerHiveView/parse_peer_hives
references after the removal — none left.

hive-c0re/src/dashboard/state_snapshot.rs

@@ -120,12 +120,6 @@ pub(super) struct StateSnapshot {
     /// var, set from `services.hyperhive.swarm.name`. `None` when
     /// unset — chrome omits the swarm segment of the breadcrumb.
     swarm_name: Option<String>,
-    /// Peer hives in the same swarm. Parsed from `HYPERHIVE_PEERS`
-    /// (JSON array of `{domain,cert_fingerprint}` objects, emitted by
-    /// the c0re NixOS module from `services.hyperhive.swarm.peerHives`
-    /// — the swarm's `hives` directory minus this hive).
-    /// Empty on single-hive deploys. Feeds the P33RS dashboard tab.
-    peer_hives: Vec<PeerHiveView>,
     /// Server-level warnings for the dashboard's top-of-page banner
     /// (currently host disk-pressure; more producers can be added
     /// backend-side). Empty when all clear. Built by
@@ -161,18 +155,6 @@ async fn infra_container_views() -> Vec<InfraContainerView> {
     infra_containers
 }
 
-/// One peer hive for the P33RS dashboard tab. Derived from
-/// `HYPERHIVE_PEERS` env; `url` is the peer's HTTPS dashboard root.
-/// `cert_fingerprint` is `Some("sha256:<hex64>")` when the operator
-/// pinned the peer's leaf in `services.hyperhive.swarm.hives`, which a
-/// hive under the swarm root CA does not need.
-#[derive(Serialize)]
-struct PeerHiveView {
-    name: String,
-    url: String,
-    cert_fingerprint: Option<String>,
-}
-
 /// `OpQuestion` + computed `question_refs` / `answer_refs`. Built
 /// from the snapshot read; the live channel attaches the same
 /// fields directly on `QuestionAdded` / `QuestionResolved`.
@@ -442,64 +424,11 @@ pub(super) async fn api_state(
         swarm_name: std::env::var("HYPERHIVE_SWARM_NAME")
             .ok()
             .filter(|s| !s.is_empty()),
-        peer_hives: parse_peer_hives(),
         server_warnings,
         infra_containers,
     })
 }
 
-/// Parse `HYPERHIVE_PEERS` env var into dashboard-ready `PeerHiveView`
-/// entries. The env var is a JSON array of `{domain, cert_fingerprint}`
-/// objects emitted by the c0re NixOS module from
-/// `services.hyperhive.swarm.peerHives`. Each entry becomes
-/// `{ name: domain, url: "https://domain/" }` for the P33RS tab.
-/// Returns empty vec when unset (single-hive deploy).
-fn parse_peer_hives() -> Vec<PeerHiveView> {
-    #[derive(serde::Deserialize)]
-    struct Raw {
-        domain: String,
-        cert_fingerprint: Option<String>,
-    }
-    let Ok(json) = std::env::var("HYPERHIVE_PEERS") else {
-        return Vec::new();
-    };
-    let Ok(raw): Result<Vec<Raw>, _> = serde_json::from_str(&json) else {
-        tracing::warn!("HYPERHIVE_PEERS is not valid JSON; ignoring");
-        return Vec::new();
-    };
-    raw.into_iter()
-        .map(|r| {
-            let cert_fingerprint = r.cert_fingerprint.and_then(|fp| {
-                if validate_cert_fingerprint(&fp) {
-                    Some(fp)
-                } else {
-                    tracing::warn!(
-                        domain = %r.domain,
-                        fingerprint = %fp,
-                        "HYPERHIVE_PEERS: invalid cert_fingerprint format \
-                         (expected `sha256:<64 hex chars>`); ignoring fingerprint"
-                    );
-                    None
-                }
-            });
-            PeerHiveView {
-                name: r.domain.clone(),
-                url: format!("https://{}/", r.domain),
-                cert_fingerprint,
-            }
-        })
-        .collect()
-}
-
-/// Validate a TLS certificate fingerprint string from `HYPERHIVE_PEERS`.
-/// Accepts `sha256:<64 hex chars>` (upper or lower case).
-fn validate_cert_fingerprint(fp: &str) -> bool {
-    let Some(hex) = fp.strip_prefix("sha256:") else {
-        return false;
-    };
-    hex.len() == 64 && hex.chars().all(|c| c.is_ascii_hexdigit())
-}
-
 /// Group live containers by their assigned web UI port; clusters with
 /// more than one member are port-hash collisions the operator needs
 /// to resolve by renaming. Manager (fixed at 8000) and sub-agents