chore(main): release 5.2.0

[github-actions]

🤖 I have created a release beep boop

5.2.0 (2026-05-11)

Features

• client: server_version constructor scaffold (stage 7-lite) (#674) (5c7acb4)
• client: surface structured adcp_error on TaskResult (#675) (fe66335)
• compat: AdapterPair pattern + v2.5 sync_creatives (stage 4) (#665) (0e47dcc)
• compat: server-side shape-based v2.5 detection (stage 6) (#673) (d6210cc)
• compat: v2.5 create_media_buy + update_media_buy adapters (stage 5c) (#669) (4e3473a)
• compat: v2.5 get_products adapter (stage 5b) (#668) (2025520)
• compat: v2.5 list_creative_formats + preview_creative adapters; deprecate spec_compat_hooks (#667) (fec91d6)
• schemas: fetch + bundle v2.5 schemas from pinned upstream SHA (stage 4b1) (#670) (bd6837f)
• server: pre-adapter validation against legacy schema (stage 4b2) (#671) (4ef032b)
• server: route validation by wire adcp_version (stage 3) (#664) (d2ffac7)
• validation: per-version validator loader (stage 2 of versioned validation) (#659) (6311a9a)

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[github-actions]

🤖 Created releases:

• v5.2.0

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