* fix(media): honor sender policy for host media reads
* fix(media): clarify host read group policy gating
* fix(media): forward sender identity for outbound reads
* fix(media): propagate non-id sender fields through outbound session for e164/username/name policy matching
* fix(media): preserve requester provider for host read policy
* fix(media): forward full sender identity through followup and core send paths
* fix(media): forward requester session/account context through core send fallback
* fix(media): preserve account policy fallback for requester-scoped host reads
* chore(changelog): add outbound media sender-policy entry
* fix(media): align test call shape with production — omit messageProvider when sessionKey is set
Addresses P2 review: production call sites pass messageProvider: undefined
when sessionKey is present; tests should mirror that so regressions in
the precedence order are caught.
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Co-authored-by: Devin Robison <drobison@nvidia.com>