SSH connection status indicators

- Add Connected bool field to vfs.Entry and RemoteMount
- Track connection status in sshState.connectedHosts
- Show status icon (connected/disconnected) in pane header when browsing remote host
- Async SSH connection test with cancel support for Add Host dialog
- Colored labels and styled help text in SSH dialogs
- Confirmation dialog when deleting manually-added SSH hosts

vendor/modules.txt

@@ -45,6 +45,9 @@ github.com/dlclark/regexp2/syntax
 # github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f
 ## explicit; go 1.16
 github.com/erikgeiser/coninput
+# github.com/kr/fs v0.1.0
+## explicit
+github.com/kr/fs
 # github.com/lucasb-eyer/go-colorful v1.2.0
 ## explicit; go 1.12
 github.com/lucasb-eyer/go-colorful
@@ -74,16 +77,31 @@ github.com/pelletier/go-toml/v2/internal/characters
 github.com/pelletier/go-toml/v2/internal/danger
 github.com/pelletier/go-toml/v2/internal/tracker
 github.com/pelletier/go-toml/v2/unstable
+# github.com/pkg/sftp v1.13.10
+## explicit; go 1.23.0
+github.com/pkg/sftp
+github.com/pkg/sftp/internal/encoding/ssh/filexfer
+github.com/pkg/sftp/internal/encoding/ssh/filexfer/openssh
 # github.com/rivo/uniseg v0.4.7
 ## explicit; go 1.18
 github.com/rivo/uniseg
 # github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e
 ## explicit; go 1.19
 github.com/xo/terminfo
-# golang.org/x/sys v0.38.0
-## explicit; go 1.24.0
+# golang.org/x/crypto v0.50.0
+## explicit; go 1.25.0
+golang.org/x/crypto/blowfish
+golang.org/x/crypto/chacha20
+golang.org/x/crypto/curve25519
+golang.org/x/crypto/internal/alias
+golang.org/x/crypto/internal/poly1305
+golang.org/x/crypto/ssh
+golang.org/x/crypto/ssh/internal/bcrypt_pbkdf
+# golang.org/x/sys v0.43.0
+## explicit; go 1.25.0
+golang.org/x/sys/cpu
 golang.org/x/sys/unix
 golang.org/x/sys/windows
-# golang.org/x/text v0.3.8
-## explicit; go 1.17
+# golang.org/x/text v0.36.0
+## explicit; go 1.25.0
 golang.org/x/text/transform