feat(wireless+ports): RF Health panels + physical per-port clients (v0.16.1-beta)

Wireless RF Health (fleet Wireless page + per-AP Radios tab):
- Channel usage map across 2.4/5/6 GHz with co-channel overlap; operating
  channel resolved live from /interface/wifi/monitor on the wifi package
  (auto-channel radios report no frequency in /print).
- AP deployment density: client RSSI distribution on the -90..-30 dBm scale
  with a coverage-gap warning.
- AP radio TX retries histogram (0%->35%+) with band selector, derived from
  per-client CCQ (new wireless_radio_quality InfluxDB series).
- WiFi connectivity success funnel (Association/Auth/DHCP) derived from logs.

Per-port connected clients (Ports tab):
- New card lists clients physically connected to a selected port (host/MAC/
  IP/VLAN/connection time, linked to client pages).
- Distinguishes physical clients from the raw MAC table: uplink/trunk ports
  are auto-detected (topology neighbor, multi-VLAN MAC spread, or high MAC
  count) and show an uplink explainer + "view MAC table" disclosure instead
  of every reachable MAC.
- Added clients.first_seen ("connected since"); set once, preserved across polls.

frontend/src/types/index.ts

@@ -118,6 +118,28 @@ export interface SwitchPort extends Interface {
   bridgeInfo?: BridgeVlanEntry | null;
 }
 
+export interface PortClient {
+  mac_address: string;
+  hostname: string | null;
+  custom_name: string | null;
+  vendor: string | null;
+  ip_address: string | null;
+  client_type: string;
+  vlan_id: number | null;
+  signal_strength: number | null;
+  first_seen: string | null;
+  last_seen: string | null;
+}
+
+export interface PortClientsResult {
+  classification: 'access' | 'uplink';
+  reason: string;
+  mac_count: number;
+  vlan_count: number;
+  neighbor: { neighbor_identity: string | null; neighbor_platform: string | null } | null;
+  clients: PortClient[];
+}
+
 export interface PortMonitorData {
   // Link state
   status?: string;
@@ -342,6 +364,52 @@ export interface WirelessMetricPoint {
   noise_floor?: number;
 }
 
+// ─── RF Health ──────────────────────────────────────────────────────────────
+
+export interface RfChannelRow {
+  device_id: number;
+  device_name: string;
+  name: string;
+  ssid?: string;
+  band?: string;
+  frequency: number;
+  channel_width?: string;
+  registered_clients: number;
+}
+
+export interface RfSignalRow {
+  mac_address: string;
+  signal_strength: number;
+  device_id: number;
+  device_name: string;
+  custom_name?: string | null;
+  hostname?: string | null;
+}
+
+export interface RfTxQualityRow {
+  device_id: string;
+  device_name?: string;
+  interface: string;
+  band: string;
+  tx_retry_pct: number;
+}
+
+export interface RfConnectivityStage {
+  success: number;
+  failure: number;
+  pct: number | null;
+}
+
+export interface RfConnectivity {
+  range: string;
+  log_derived: boolean;
+  stages: {
+    association: RfConnectivityStage;
+    authentication: RfConnectivityStage;
+    dhcp: RfConnectivityStage;
+  };
+}
+
 export interface ConfigSnapshotMeta {
   id: number;
   device_id: number;