New endpoint: GET /v1/analytics/content/attribution

[freddyDOTCMS]

Description

Create a new endpoint GET /v1/analytics/content/attribution that returns content items ranked by how often they appeared in a conversion path.

Improvement plan: https://docs.google.com/document/d/1hVfIurPqAJJ1PN1EalmvrWXnGNt5sY21MI-409lrXpU/edit?tab=t.klqavlz4cis7#heading=h.8vek9yxwq8yt

Parent epic: #35048

Query Parameters

Param	Required	Description
siteId	✅	dotCMS site identifier
environment	✅	Cluster/environment identifier
from + to OR range	✅	Time range — absolute or relative
eventType	❌	Filter by event type
identifier	❌	Filter by content identifier
title	❌	Filter by content title
orderBy	❌	title, identifier, eventType, attributionRate, attributionCount
orderDir	❌	asc or desc
page	❌	Page number (pagination)
pageSize	❌	Results per page

Headers

X-Customer-Id, X-Signature (HMAC-SHA256)

Time range rules

• If from/to present → use them, ignore range
• Else if range present → compute from/to

Response shape

{
  "params": { "siteId": "...", "environment": "...", "from": "...", "to": "..." },
  "pagination": { "page": 1, "pageSize": 50, "totalPages": 4, "totalItems": 180 },
  "data": [
    {
      "eventType": "content_click",
      "identifier": "f9e8d7c6-uuid",
      "title": "Download Our Guide CTA",
      "attributionCount": 75,
      "events": 310,
      "attributionRate": 24.19
    }
  ]
}

Acceptance Criteria

• GET /v1/analytics/content/attribution endpoint created
• Mandatory params validated: siteId, environment, time range — returns 400 when missing
• Optional params work: eventType, identifier, title filter results correctly
• orderBy supports all five values; orderDir defaults to desc
• Pagination works: page + pageSize with correct totalPages / totalItems in response
• Time range rules applied: absolute takes precedence over relative
• X-Customer-Id enforces row-level data isolation
• X-Signature validated (HMAC-SHA256)
• Response matches the documented JSON shape

Additional Context

• Source task: Conversion dashboard endpoints / Conversion Endpoint Detail changes
• Requires Phase 2 completion — blocked by: Update ClickHouse Materialized Views after lookup table removal #35062
• Related branch: issue-34849-Add-dotCMS-Analytics-Proxy-Endpoint-for-/v1/analytics/-to-dot-ca-event-manager