Include attachments in create-evidence output

[mnsboev]

Summary

• Add an Attachments []CreateResponseAttachment field to model.CreateResponse, mirroring the evidence service AttachmentView schema (name, sha256, type, download_path) so the create response body unmarshals directly.
• Render attachment rows in the create-evidence table output (attachment.<field> for one attachment, attachments[i].<field> for multiple). Empty fields are skipped, matching the existing field rendering convention.
• download_path is intentionally JSON-only: it's a long opaque string that distorts the table layout without offering eyeball value; scripted callers that need it should use --format json.
• Tests cover JSON output (full attachment incl. download_path), table output (single/empty-fields/multiple attachments), download_path is asserted to NOT leak into the table, and uploadEvidence faithfully passes through server-returned attachments.

What it looks like

--format table (single attachment):

│ provider_id       │ jfrog                                            │
│ attachment.name   │ slsa-provenance-1774941162594-c092e7b4.json      │
│ attachment.sha256 │ 7dbd94658f313ccfc811e28ad40408c48666dc9a19233... │
│ attachment.type   │ application/json                                 │

--format json (truncated):

{
  ...,
  "attachments": [
    {
      "name": "slsa-provenance-1774941162594-c092e7b4.json",
      "sha256": "7dbd94658f313ccfc811e28ad40408c48666dc9a19233d0a278140557d9a573f",
      "type": "application/json",
      "download_path": "my-repo/.evidence/76ce53.../7dbd94.../slsa-provenance-...json"
    }
  ]
}

Test plan

• go build ./... clean
• go vet ./... clean on affected packages
• go test ./evidence/model/... ./evidence/create/... ./evidence/cli/command/... -count=1 — 348 passed
• Manual: run jf evd create --attach-artifactory-path ... --format json against a current evidence service; confirm attachments[] is populated with name/sha256/type/download_path
• Manual: same with --format table; confirm three attachment.* rows appear and download_path is absent
• Manual: run jf evd create without any --attach-* flag; confirm output is unchanged from current behavior (no attachments key in JSON, no attachment rows in table)

[github-actions]

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