Function validateSkillExecution

Skills module exports (Voyager-style skill library) - Issue #528 Split from agents.ts for file size compliance (Issue #285)

validateSkillExecution(
    agentRole: AgentRole,
    capabilities: SkillCapabilities,
    rbac: SkillRBAC,
    requestedPermissions: readonly SkillPermission[],
): Result<void, SkillSecurityError>
Performs comprehensive security validation for skill execution.
Parameters
- agentRole: AgentRole
  The role of the agent attempting execution
- capabilities: SkillCapabilities
  The skill's capabilities
- rbac: SkillRBAC
  The skill's RBAC configuration
- requestedPermissions: readonly SkillPermission[]
  Permissions needed for the operation
Returns Result<void, SkillSecurityError>
Result indicating success or the first validation error
- Defined in packages/nexus-agents/src/agents/skills/skill-security.ts:318