feat(api): add GET /api/actions/unified endpoint (closes #155)

[akuraposo]

Summary

Implements GET /api/actions/unified — a merged, paginated action log endpoint that combines Instagram and Twitter actions into a single consistent JSON schema. Closes #155.

This delivers the Unified action log (IG/Twitter/GitHub) roadmap item under 3) Data and Storage. GitHub actions are stubbed/omitted per the spec; the focus is on the IG + Twitter merge.

Endpoint

GET /api/actions/unified
Auth: JWT cookie (same as other /api/actions/* routes)

Query params

param	default	notes
limit	20	max 100
offset	0
account	—	optional account filter
status	—	success or error
sort	desc	asc or desc (by timestamp)

Response shape

{
  "actions": [
    {
      "platform": "twitter",
      "action": "tweet",
      "timestamp": "2026-07-01T11:00:00.000Z",
      "status": "success",
      "metadata": {
        "id": "tw-1",
        "account": "default",
        "username": "tw_user",
        "error": null,
        "details": { "tweetId": "999" }
      }
    }
  ],
  "pagination": { "total": 2, "limit": 20, "offset": 0, "hasMore": false }
}

Each action has the consistent shape required by the bounty: platform, action, timestamp, status, and metadata.

Implementation notes

• Fetches IG and Twitter logs in parallel via the existing listActionLogs service (with platform filter), over-fetching (limit * 2 per platform, capped at 100) so that after merging + sorting + paginating the caller still gets a full page in the common case.
• Merges client-side, sorts by timestamp (newest first by default), then paginates.
• Reuses the existing ActionLogStatus type and listActionLogs service — no new DB schema, no new file-based store.
• Registered in the /api/docs endpoint list so it shows up in the API documentation.

Acceptance criteria checklist

• GET /api/actions/unified responds with HTTP 200
• Response includes actions from both IG and Twitter sources in one array
• Each action has a consistent shape: platform, action, timestamp, status, and metadata
• Supports pagination via ?limit= and ?offset= query params
• Includes at least one test in apps/api/src/routes/api.test.ts (4 new tests added)
• PR references this issue (closes #155)

Tests

4 new test cases in apps/api/src/routes/api.test.ts, all passing:

1. responds with 401 without authentication
2. returns a merged, paginated IG + Twitter action log — verifies both platforms present, consistent shape, sorted desc by timestamp, pagination metadata
3. honours limit and offset pagination params
4. returns 500 when the action log service throws

PASS src/routes/api.test.ts
Tests: 16 passed, 16 total

Closes #155

/claim #155