v1.1.0

Adds optional compare-and-set (if_version) and write idempotency
(operation_id) to memory_set. Both default to off, so existing callers
are unaffected.

The memory_set write path moves from a non-atomic ioredis pipeline to a
single Lua EVAL. Besides making the compare-and-set a guarantee rather
than a race, this fixes a pre-existing bug where concurrent writes
interleaved index maintenance and left an entry in tag index sets it no
longer belonged to. Upgrading stops new corruption but does not clean
existing stale memberships.

Adds the memory_conflict_total metric and
MEMORY_MCP_OPERATION_ID_TTL_SECONDS.