Feature request: Support for 'explode' parameter in OpenAPI 3.x array query parameters

[curiosity-the-rover]

Description

When generating OpenAPI 3.x specs with -v3.1 flag, there's no way to specify explode: false for array query parameters.

Current Behavior

Using collectionFormat(csv) annotation:

// @Param ids query []string false "Filter by IDs" collectionFormat(csv)

Generates:

- name: ids
  in: query
  schema:
    type: array
    items:
      type: string
  style: form

The explode property is missing, which defaults to true per OpenAPI 3.x spec.

Expected Behavior

Ability to generate explode: false for comma-separated array serialization:

- name: ids
  in: query
  schema:
    type: array
    items:
      type: string
  style: form
  explode: false

Proposed Solution

Add support for explode(false) or explode(true) annotation:

// @Param ids query []string false "Filter by IDs" style(form) explode(false)

Or extend collectionFormat to properly map to OpenAPI 3.x:

• collectionFormat(csv) → style: form, explode: false
• collectionFormat(multi) → style: form, explode: true

Use Case

This is needed for API contracts where the frontend expects comma-separated arrays (?ids=a,b,c) instead of repeated parameters (?ids=a&ids=b&ids=c).

Environment

• swag version: v2.0.0-rc5 (binary reports as v2.0.0)
• Go version: 1.25.4
• Using -v3.1 flag for OpenAPI 3.1 generation