feat: add Go SSH config management functions and type

7 funciones Go del dominio infra para gestion programatica de ~/.ssh/config:
ssh_config_parse (parser de bloques Host/Match), ssh_config_read (lectura del
archivo), ssh_config_find (busqueda por host), ssh_config_add_entry y
ssh_config_remove_entry (CRUD), ssh_config_render (serializacion a texto),
ssh_config_write (escritura atomica). Incluye tipo SshConfigEntry (product type)
y tests unitarios del parser.

functions/infra/ssh_config_parse.go

@@ -0,0 +1,84 @@
+package infra
+
+import (
+	"bufio"
+	"strconv"
+	"strings"
+)
+
+// SSHConfigParse parsea el contenido de un archivo ~/.ssh/config y retorna
+// una lista de SSHConfigEntry. Ignora comentarios y lineas vacias.
+// Los bloques Host con wildcards (* o ?) se ignoran.
+func SSHConfigParse(content string) []SSHConfigEntry {
+	var entries []SSHConfigEntry
+	var current *SSHConfigEntry
+
+	scanner := bufio.NewScanner(strings.NewReader(content))
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+
+		key, value := splitDirective(line)
+		if key == "" {
+			continue
+		}
+
+		if strings.EqualFold(key, "Host") {
+			if current != nil && current.Alias != "" {
+				entries = append(entries, *current)
+			}
+			if strings.ContainsAny(value, "*?") {
+				current = nil
+				continue
+			}
+			current = &SSHConfigEntry{
+				Alias:   value,
+				Options: make(map[string]string),
+			}
+			continue
+		}
+
+		if current == nil {
+			continue
+		}
+
+		switch strings.ToLower(key) {
+		case "hostname":
+			current.HostName = value
+		case "user":
+			current.User = value
+		case "port":
+			if p, err := strconv.Atoi(value); err == nil {
+				current.Port = p
+			}
+		case "identityfile":
+			current.IdentityFile = value
+		default:
+			current.Options[key] = value
+		}
+	}
+
+	if current != nil && current.Alias != "" {
+		entries = append(entries, *current)
+	}
+	return entries
+}
+
+// splitDirective separa una linea "Key Value" o "Key=Value" en clave y valor.
+func splitDirective(line string) (string, string) {
+	// Intentar separar por =
+	if idx := strings.IndexByte(line, '='); idx >= 0 {
+		return strings.TrimSpace(line[:idx]), strings.TrimSpace(line[idx+1:])
+	}
+	// Separar por primer espacio/tab
+	fields := strings.SplitN(line, " ", 2)
+	if len(fields) < 2 {
+		fields = strings.SplitN(line, "\t", 2)
+	}
+	if len(fields) < 2 {
+		return "", ""
+	}
+	return strings.TrimSpace(fields[0]), strings.TrimSpace(fields[1])
+}