feat: add alias file generation and management for shell hooks

- **Aliases**: Generate shell alias files (`aliases.sh` for bash/zsh, `netssh.fish` for fish) from cached hosts. Regenerate on each shell startup and cache refresh to keep aliases updated.
- **Hooks**: Extend shell hook functionality to include alias file support. Install and uninstall commands updated for bash, zsh, and fish.
- **Tests**: Add unit tests to verify alias file generation, path resolution, and idempotent hook installation.
- **Docs**: Update README with instructions for alias file usage, installation, and relation to hooks.

internal/hook/hook.go

@@ -8,10 +8,15 @@ import (
 )
 
 const (
-	// Marker is the unique string used to detect an existing hook installation.
+	// Marker is the unique string used to detect an existing hook line.
 	Marker = "netssh shell-init"
 	// Line is the full line written into the shell profile.
 	Line = "netssh shell-init  # netssh cache auto-refresh"
+
+	// AliasesMarker is the unique string used to detect the aliases source line.
+	AliasesMarker = "netssh/aliases.sh"
+	// AliasesSourceLine is the bash/zsh line that sources the generated aliases file.
+	AliasesSourceLine = "source ~/.cache/netssh/aliases.sh 2>/dev/null  # netssh aliases"
 )
 
 // ProfilePath returns the canonical shell profile path for the given shell name.
@@ -68,8 +73,30 @@ func Install(profilePath string) (installed bool, err error) {
 	return true, nil
 }
 
-// Uninstall removes the hook line from the profile.
-// Returns (true, nil) when removed, (false, nil) when the hook was not found.
+// InstallAliasesSource appends the aliases source line to a bash/zsh profile.
+// This is a no-op for fish (which uses conf.d auto-sourcing instead).
+// Returns (true, nil) when newly added, (false, nil) when already present.
+func InstallAliasesSource(profilePath string) (installed bool, err error) {
+	data, err := os.ReadFile(profilePath)
+	if err != nil && !os.IsNotExist(err) {
+		return false, fmt.Errorf("reading profile: %w", err)
+	}
+	if strings.Contains(string(data), AliasesMarker) {
+		return false, nil
+	}
+	f, err := os.OpenFile(profilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
+	if err != nil {
+		return false, fmt.Errorf("opening profile: %w", err)
+	}
+	defer f.Close()
+	if _, err := fmt.Fprintf(f, "%s\n", AliasesSourceLine); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// Uninstall removes the hook line and the aliases source line from the profile.
+// Returns (true, nil) when something was removed, (false, nil) when nothing was found.
 // Returns (false, nil) — not an error — when the file does not exist.
 func Uninstall(profilePath string) (removed bool, err error) {
 	data, err := os.ReadFile(profilePath)
@@ -80,13 +107,13 @@ func Uninstall(profilePath string) (removed bool, err error) {
 		return false, fmt.Errorf("reading profile: %w", err)
 	}
 	content := string(data)
-	if !strings.Contains(content, Marker) {
+	if !strings.Contains(content, Marker) && !strings.Contains(content, AliasesMarker) {
 		return false, nil
 	}
 
 	var kept []string
 	for _, line := range strings.Split(content, "\n") {
-		if strings.Contains(line, Marker) {
+		if strings.Contains(line, Marker) || strings.Contains(line, AliasesMarker) {
 			continue
 		}
 		kept = append(kept, line)