fix(completion): offer unique hostnames without instance prefix

bash (and zsh without a matcher) only accept candidates that start with
the typed text, so "fsn1-bx1<Tab>" found nothing when every candidate
was qualified as "prod/…". Hostnames that exist in only one instance
are now offered bare; names present in several instances stay
qualified. Connecting to a bare name still checks every instance for
ambiguity, so the connection behavior is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cmd/netssh/instances.go

@@ -1,6 +1,10 @@
 package main
 
 import (
+	"sort"
+	"strings"
+
+	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/cache"
 	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/config"
 	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/netbox"
 	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/shortcuts"
@@ -30,3 +34,36 @@ func normalizeTarget(cfg config.ShortcutsConfig, qualified bool) func(string) st
 		return name
 	}
 }
+
+// hostCompletions returns the cached hosts matching toComplete in a form that
+// starts with the typed text, because bash and fish only accept such
+// candidates. Without an instance prefix, a hostname that is unique across
+// all instances is offered bare ("web01"), so it completes like with a single
+// NetBox; connecting to it still checks every instance for ambiguity.
+// Names present in several instances stay qualified ("prod/web01").
+func hostCompletions(entries []cache.Entry, toComplete string) []string {
+	prefix := strings.ToLower(toComplete)
+	qualifiedInput := strings.Contains(prefix, "/")
+	instances := make(map[string]int)
+	for _, e := range entries {
+		_, name := netbox.SplitTarget(e.Name)
+		instances[strings.ToLower(name)]++
+	}
+	var out []string
+	for _, e := range entries {
+		source, name := netbox.SplitTarget(e.Name)
+		target := strings.ToLower(e.Name)
+		switch {
+		case source != "" && !qualifiedInput && strings.HasPrefix(strings.ToLower(name), prefix):
+			if instances[strings.ToLower(name)] == 1 {
+				out = append(out, name)
+			} else {
+				out = append(out, e.Name)
+			}
+		case strings.HasPrefix(target, prefix):
+			out = append(out, e.Name)
+		}
+	}
+	sort.Strings(out)
+	return out
+}