feat: add pagination and unmigrated count to admin builders endpoint

[tim-hm]

No description provided.

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	70.88%	1466 / 2068
🔵	Statements	70.64%	1497 / 2119
🔵	Functions	72.2%	665 / 921
🔵	Branches	49.74%	298 / 599

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
packages/api/src/builders/builders.repository.ts	66.1%	56.81%	59.03%	66.1%	33-73, 96, 125, 153, 190, 223, 256, 288, 321, 344-370, 399, 448, 491, 529, 563, 585-628
packages/api/src/credits/credits.controllers.ts	73.07%	85.71%	59.37%	73.07%	75-82, 173-179, 372-390, 433-443

Generated in workflow #476 for commit 580e8d3 by the Vitest Coverage Report Action