Add shared/managed-agents-memory.md covering the Memory Stores public
beta under managed-agents-2026-04-01: object model (memstore_/mem_/
memver_), create + seed, attach via resources[] at session-create time,
FUSE mount at /mnt/memory/<store>/, host-side CRUD with create-by-path
vs update-by-id, content_sha256 preconditions, and versions/redact.
Wire it through all cross-references: SKILL.md beta-headers namespace
and reading guide; api-reference SDK method rows, delete/archive quirks
bullet, AddResource note, and three new endpoint sections; core.md
architecture diagram and resources[] enumerations; environments.md
Resources intro; overview.md beta-headers table, Reading Guide row, and
archive-is-permanent bullet.
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