feat: introduce shortcuts and shell hook support

- **Shortcuts**: Add hostname normalization with domain stripping and hyphen folding. Include alias generation for cached hosts.
- **Shell Hook**: Automate 24h cache refresh trigger with shell startup hook. Add install/uninstall commands for bash, zsh, and fish.
- **Wizard**: Extend setup wizard to configure shortcuts (domains, hyphen stripping) and default SSH port.
- **Cache**: Add `GetByShortcut` for resolving hosts via normalized shortcuts. Implement `NeedsRefresh` / `SetRefreshed` logic for refresh timestamps.
- **Tests**: Comprehensive unit tests for shortcuts, hook installation, cache refresh, and alias generation.
- **Docs**: Update README with shortcuts, shell hook, and default SSH port configuration.

internal/cache/cache_test.go

@@ -300,6 +300,164 @@ func TestMarkUsed_RoundtripViaSave(t *testing.T) {
 	}
 }
 
+// --- GetByShortcut tests ---
+
+func TestGetByShortcut_MatchFresh(t *testing.T) {
+	c := New("", 3600)
+	c.Upsert(Entry{Name: "web01.example.com", IP: "10.0.0.1", Kind: "device"})
+
+	normalize := func(s string) string {
+		// strip .example.com
+		if len(s) > len(".example.com") && s[len(s)-len(".example.com"):] == ".example.com" {
+			s = s[:len(s)-len(".example.com")]
+		}
+		return s
+	}
+
+	e, found, fresh := c.GetByShortcut("web01", normalize)
+	if !found {
+		t.Fatal("expected entry to be found")
+	}
+	if !fresh {
+		t.Error("entry just inserted should be fresh")
+	}
+	if e.IP != "10.0.0.1" {
+		t.Errorf("IP: got %q, want %q", e.IP, "10.0.0.1")
+	}
+}
+
+func TestGetByShortcut_MatchStale(t *testing.T) {
+	c := New("", 1) // 1 second TTL
+	stale := Entry{Name: "web01.example.com", IP: "10.0.0.1", Kind: "device", CachedAt: time.Now().Add(-2 * time.Second)}
+	c.mu.Lock()
+	c.entries["web01.example.com"] = stale
+	c.mu.Unlock()
+
+	normalize := func(s string) string {
+		if len(s) > len(".example.com") && s[len(s)-len(".example.com"):] == ".example.com" {
+			s = s[:len(s)-len(".example.com")]
+		}
+		return s
+	}
+
+	_, found, fresh := c.GetByShortcut("web01", normalize)
+	if !found {
+		t.Fatal("expected entry to be found even when stale")
+	}
+	if fresh {
+		t.Error("entry older than TTL should not be fresh")
+	}
+}
+
+func TestGetByShortcut_NotFound(t *testing.T) {
+	c := New("", 3600)
+	c.Upsert(Entry{Name: "db01.example.com", IP: "10.0.0.2", Kind: "device"})
+
+	_, found, _ := c.GetByShortcut("web01", func(s string) string { return s })
+	if found {
+		t.Error("should not find an entry that does not match the shortcut")
+	}
+}
+
+func TestGetByShortcut_EmptyCache(t *testing.T) {
+	c := New("", 3600)
+	_, found, _ := c.GetByShortcut("web01", func(s string) string { return s })
+	if found {
+		t.Error("empty cache should return found=false")
+	}
+}
+
+func TestGetByShortcut_MultiDomain(t *testing.T) {
+	c := New("", 3600)
+	// Entry uses second domain (.example.de)
+	c.Upsert(Entry{Name: "web01.example.de", IP: "10.0.0.5", Kind: "vm"})
+
+	normalize := func(s string) string {
+		for _, suffix := range []string{".example.com", ".example.de"} {
+			if len(s) > len(suffix) && s[len(s)-len(suffix):] == suffix {
+				return s[:len(s)-len(suffix)]
+			}
+		}
+		return s
+	}
+
+	e, found, _ := c.GetByShortcut("web01", normalize)
+	if !found {
+		t.Fatal("should match entry with second configured domain")
+	}
+	if e.IP != "10.0.0.5" {
+		t.Errorf("IP: got %q, want %q", e.IP, "10.0.0.5")
+	}
+}
+
+// --- NeedsRefresh / SetRefreshed tests ---
+// These tests require NeedsRefresh(time.Duration) bool and SetRefreshed() error
+// to be implemented on *Cache. The refreshStamp field (path to the timestamp file)
+// must be set before calling these methods.
+
+func TestNeedsRefresh_NeverRefreshed(t *testing.T) {
+	dir := t.TempDir()
+	stampPath := filepath.Join(dir, "last_refresh")
+	c := New(filepath.Join(dir, "cache.json"), 3600)
+	c.refreshStamp = stampPath
+
+	if !c.NeedsRefresh(24 * time.Hour) {
+		t.Error("NeedsRefresh should return true when last_refresh file does not exist")
+	}
+}
+
+func TestNeedsRefresh_JustRefreshed(t *testing.T) {
+	dir := t.TempDir()
+	stampPath := filepath.Join(dir, "last_refresh")
+	c := New(filepath.Join(dir, "cache.json"), 3600)
+	c.refreshStamp = stampPath
+
+	if err := c.SetRefreshed(); err != nil {
+		t.Fatalf("SetRefreshed: %v", err)
+	}
+	if c.NeedsRefresh(24 * time.Hour) {
+		t.Error("NeedsRefresh should return false immediately after SetRefreshed")
+	}
+}
+
+func TestNeedsRefresh_Stale(t *testing.T) {
+	dir := t.TempDir()
+	stampPath := filepath.Join(dir, "last_refresh")
+	// Write a timestamp 25 hours ago
+	oldTime := time.Now().Add(-25 * time.Hour).Format(time.RFC3339)
+	if err := os.WriteFile(stampPath, []byte(oldTime), 0o644); err != nil {
+		t.Fatalf("writing stamp: %v", err)
+	}
+
+	c := New(filepath.Join(dir, "cache.json"), 3600)
+	c.refreshStamp = stampPath
+
+	if !c.NeedsRefresh(24 * time.Hour) {
+		t.Error("NeedsRefresh should return true when last_refresh is older than duration")
+	}
+}
+
+func TestSetRefreshed_Roundtrip(t *testing.T) {
+	dir := t.TempDir()
+	stampPath := filepath.Join(dir, "last_refresh")
+	c := New(filepath.Join(dir, "cache.json"), 3600)
+	c.refreshStamp = stampPath
+
+	if err := c.SetRefreshed(); err != nil {
+		t.Fatalf("SetRefreshed: %v", err)
+	}
+
+	// Just refreshed: 24h window → not stale
+	if c.NeedsRefresh(24 * time.Hour) {
+		t.Error("NeedsRefresh(24h) should be false right after SetRefreshed")
+	}
+
+	// Zero duration: everything is stale
+	if !c.NeedsRefresh(0) {
+		t.Error("NeedsRefresh(0) should always return true")
+	}
+}
+
 // tempFile writes content to a temp file and returns its path.
 func tempFile(t *testing.T, content []byte) string {
 	t.Helper()