feat(seer): Add bulk Seer project connected repos endpoint

[srest2021]

Fixes CW-1286

Depends on #115199 and #115904

Adds a bulk Seer project repos endpoint ProjectSeerReposEndpoint (GET/POST/PUT) at /api/0/projects/{org}/{project}/seer/repos/ with ProjectPermission.

GET — List connected repos

Lists all connected Seer project repos for a project. Supports search by name (substring, case-insensitive) and provider (exact match, supports =, !=, IN, NOT IN, with or without integrations: prefix), sorting by name/-name/provider/-provider, and offset pagination. Excludes inactive repos and unsupported providers.

GET /api/0/projects/my-org/my-project/seer/repos/?query=relay&sortBy=-name

POST — Add repos

Upserts repos by ID. Validates all repo IDs are active, belong to the org, and have supported providers — returns 400 with invalid IDs if not. Rejects empty lists, duplicate repo IDs, and duplicate branch overrides.

POST /api/0/projects/my-org/my-project/seer/repos/
{
  "repos": [
    {"repositoryId": 1, "branchName": "main", "instructions": "use pytest"},
    {"repositoryId": 2, "branchOverrides": [
      {"tagName": "environment", "tagValue": "production", "branchName": "release"}
    ]}
  ]
}

PUT — Replace all repos

Replaces all connected repos for the project atomically. Accepts an empty list to disconnect all repos. Same validation as POST for non-empty lists.

PUT /api/0/projects/my-org/my-project/seer/repos/
{
  "repos": [
    {"repositoryId": 3, "branchName": "develop"}
  ]
}

[linear-code]

CW-1286

[cursor]

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