Release v0.52.0-nightly.20260714.gfa975395b

What's Changed

• fix(core): enrich shared project quota limit errors with setup hint by @amelidev in #28391
• fix(a2a-server): ensure task cancellation aborts execution loop by @luisfelipe-alt in #28316
• fix(core): simplify plan mode write policy to support relative paths by @DavidAPierce in #28398
• feat(core): Bump node google-auth-library version to 10.9.0 by @jerrylin3321 in #28385

Full Changelog: v0.52.0-nightly.20260713.gf354eebaf...v0.52.0-nightly.20260714.gfa975395b