feat: Super Check Partial + N+1 helper; fix Flex binding to SmartSDR CAT; telemetry callsign wait

- SCP/N+1: new internal/scp downloads the community MASTER.SCP master list and a
  docked two-column widget shows, as you type a call, the known calls containing it
  (Partial) and the calls one edit away (N+1) — click to fix a busted call. Opt-in
  in Settings → General; top-bar toggle; queried debounced on callsign input.
- Flex: OpsLog's GUI-client detection was too loose and could bind to "SmartSDR CAT"
  (or DAX) — both carry "smartsdr" in the program name — instead of the real GUI
  client, making SmartSDR CAT drop and reconnect in a loop while OpsLog was open.
  Now it binds only to a real SmartSDR/Maestro GUI client (e.g. a FLEX-8600M's
  integrated screen) and excludes cat/dax; dropped the risky empty-program fallback.
- Telemetry: on a fresh install the callsign isn't set at launch, so the once-a-day
  heartbeat recorded the machine UUID. Now it waits (~10 min) for the operator to
  enter their callsign before sending, falling back to the UUID only if none appears.

app.go

@@ -53,6 +53,7 @@ import (
 	"hamlog/internal/rotator/gs232"
 	"hamlog/internal/rotator/pst"
 	"hamlog/internal/rotgenius"
+	"hamlog/internal/scp"
 	"hamlog/internal/settings"
 	"hamlog/internal/solar"
 	"hamlog/internal/spe"
@@ -234,6 +235,8 @@ const (
 
 	keyClusterAutoConnect = "cluster.auto_connect" // open every enabled server at app start
 
+	keyScpEnabled = "scp.enabled" // Super Check Partial / N+1 suggestions on
+
 	keyBackupEnabled  = "backup.enabled"
 	keyBackupFolder   = "backup.folder"
 	keyBackupRotation = "backup.rotation"
@@ -493,6 +496,7 @@ type App struct {
 	qsoRec         *audio.Recorder    // continuous QSO recorder (rolling pre-roll)
 	solar          *solar.Manager     // live space-weather (SFI/SSN/A/K) for the header + QSO stamping
 	lotwUsers      *lotwusers.Manager // LoTW user-activity list (badge next to the callsign)
+	scp            *scp.Manager       // Super Check Partial / N+1 callsign master list
 
 	// NET Control: persistent net definitions/rosters (global JSON) + the live
 	// session (in-memory only — active stations currently in QSO).
@@ -985,6 +989,25 @@ func (a *App) startup(ctx context.Context) {
 			}
 		}
 	}()
+
+	// Super Check Partial / N+1: load the cached MASTER.SCP; when the feature is
+	// enabled, auto-(re)download it if missing or older than a week.
+	a.scp = scp.NewManager(dataDir)
+	go func() {
+		if v, _ := a.settings.Get(a.ctx, keyScpEnabled); v != "1" {
+			return
+		}
+		if a.scp.Count() == 0 || time.Since(a.scp.Updated()) > 7*24*time.Hour {
+			if n, err := a.scp.Download(context.Background()); err == nil {
+				applog.Printf("scp: auto-downloaded %d callsigns", n)
+				if a.ctx != nil {
+					wruntime.EventsEmit(a.ctx, "scp:updated")
+				}
+			} else {
+				applog.Printf("scp: auto-download failed: %v", err)
+			}
+		}
+	}()
 	go func() {
 		_ = a.clublog.EnsureLoaded()
 		// Auto-refresh a missing/stale country file (ClubLog adds date-ranged
@@ -2311,6 +2334,76 @@ func (a *App) DownloadLoTWUsers() (int, error) {
 	return a.lotwUsers.Download(a.ctx)
 }
 
+// ── Super Check Partial / N+1 ────────────────────────────────────────────────
+
+// ScpStatus is the loaded-list summary for Settings + the widget gate.
+type ScpStatus struct {
+	Enabled bool   `json:"enabled"`
+	Count   int    `json:"count"`
+	Updated string `json:"updated,omitempty"` // RFC3339, empty if never
+}
+
+// GetScpStatus returns whether SCP is enabled and how many calls are loaded.
+func (a *App) GetScpStatus() ScpStatus {
+	st := ScpStatus{}
+	if a.settings != nil {
+		v, _ := a.settings.Get(a.ctx, keyScpEnabled)
+		st.Enabled = v == "1"
+	}
+	if a.scp != nil {
+		st.Count = a.scp.Count()
+		if u := a.scp.Updated(); !u.IsZero() {
+			st.Updated = u.UTC().Format(time.RFC3339)
+		}
+	}
+	return st
+}
+
+// SetScpEnabled turns Super Check Partial on/off. Enabling triggers a background
+// download when the list is missing or stale.
+func (a *App) SetScpEnabled(on bool) error {
+	if a.settings == nil {
+		return fmt.Errorf("db not initialized")
+	}
+	if err := a.settings.Set(a.ctx, keyScpEnabled, boolStr(on)); err != nil {
+		return err
+	}
+	if on && a.scp != nil && (a.scp.Count() == 0 || time.Since(a.scp.Updated()) > 7*24*time.Hour) {
+		go func() {
+			if n, err := a.scp.Download(context.Background()); err == nil {
+				applog.Printf("scp: downloaded %d callsigns", n)
+				if a.ctx != nil {
+					wruntime.EventsEmit(a.ctx, "scp:updated")
+				}
+			} else {
+				applog.Printf("scp: download failed: %v", err)
+			}
+		}()
+	}
+	return nil
+}
+
+// DownloadScp fetches the MASTER.SCP master file and caches it. Returns the
+// number of callsigns loaded.
+func (a *App) DownloadScp() (int, error) {
+	if a.scp == nil {
+		return 0, fmt.Errorf("not initialized")
+	}
+	return a.scp.Download(a.ctx)
+}
+
+// ScpLookup returns the Super Check Partial (substring) and N+1 (one-edit)
+// suggestions for a typed fragment. Empty when SCP is disabled.
+func (a *App) ScpLookup(fragment string) scp.Result {
+	if a.scp == nil || a.settings == nil {
+		return scp.Result{}
+	}
+	if v, _ := a.settings.Get(a.ctx, keyScpEnabled); v != "1" {
+		return scp.Result{}
+	}
+	return a.scp.Lookup(fragment, 60)
+}
+
 // StationInfoComputed bundles the data we resolve live from the
 // profile's callsign + grid: country, ARRL DXCC#, CQ zone, ITU zone,
 // lat/lon. Used by the Settings UI to show the "what will be stamped on