⛔ Draft — blocked by #2540 (do not merge yet)

This PR is intentionally opened as a draft. It is item #2 of the FC-0118
Studio-API caller migration tracked in #3127,
and it is on hold pending #2540 (the "Studio Home" Redux → React Query +
Context refactor). #2540 intends to break the kitchen-sink Studio Home state
(course list, library list, permissions, feature flags, branding) into smaller,
purpose-specific queries; versioning this endpoint as-is would entrench a payload
shape we plan to remove. Do not merge until #2540's direction is settled.

Merge order / dependencies

• Blocked by: Switch from Redux to React Query + Context #2540 — resolve first.
• Merge this before its sibling: the Home Courses v2 → v4 PR (item adds transifex config and test string #3 of
  Migrate Studio API callers to standardized v3/v4 endpoints (FC-0118) #3127) also edits src/studio-home/data/api.ts. Suggested order: this PR
  (Course Home [BD-03] [BB-2542] ]Add discussions configuration UI wireframe in MFE #2) first, then Home Courses adds transifex config and test string #3 rebases on top.
• Independent of the Xblock PR (item Initialize repo for new MFE, port 2001 #1 of Migrate Studio API callers to standardized v3/v4 endpoints (FC-0118) #3127).

Description

Migrates the Studio Home landing page and libraries tab reads from the
v1 endpoint to the standardized v3 endpoint (FC-0118, ADR 0028/0037):

• getStudioHomeApiUrl() now targets …/api/contentstore/v3/home/ instead of
  …/v1/home. The v3 HomeViewSet is served by a DRF DefaultRouter, so the
  URL now carries the required trailing slash.
• getStudioHomeData → GET …/v3/home/ (the aggregated list action).
• getStudioHomeLibraries → GET …/v3/home/libraries/ (the libraries
  action). The helper builds home/libraries/ off the trailing-slash base.

The default (full) response shape is unchanged between v1 and v3 (ADR 0036
?fields= presets are opt-in and default to the full payload), so this is a
behaviour-preserving swap.

Supporting information

• Tracking issue: Migrate Studio API callers to standardized v3/v4 endpoints (FC-0118) #3127 (item [BD-03] [BB-2542] ]Add discussions configuration UI wireframe in MFE #2, "Course Home v1 → v3").
• Backend v3 endpoint: HomeViewSet registered at home via DefaultRouter
  in cms/djangoapps/contentstore/rest_api/v3/urls.py; exposes
  GET /home/ (list), /home/courses/, and /home/libraries/.

Testing instructions

1. npm ci
2. npx jest src/studio-home
3. Manual: open Studio Home, confirm the landing page and the Libraries tab load,
   and that the network tab shows requests to /api/contentstore/v3/home/ and
   /api/contentstore/v3/home/libraries/.

Other information

• Files changed:
  • src/studio-home/data/api.ts — v3 base URL + trailing slash; libraries/
    concatenation fixed for the trailing-slash base.
  • src/studio-home/data/api.test.js — bump the hardcoded libraries mock to v3.
• The ~15 other test files that mock getStudioHomeApiUrl() reference it by
  function, so they track the new URL automatically.
• src/studio-home (113 tests) passes; dprint check is clean. The only
  library-authoring failures in a broad run are pre-existing, date-dependent
  flakes on master (identical failure set with and without this change).