[sec-bus] egress: local-provider endpoint classification and data-class mapping for privacy checks

Change

A "local provider endpoint" classification for LocalOnly (replaces host util/url.rs::host_is_local, which misses mapped/ULA/link-local addresses). Decide once whether RFC1918/LAN hosts count as on-device (epic note N7).
Map host EgressDescriptor (DataKind::Metadata, control-plane flag) onto PrivacyDataClass2 without loss.
Document the Sensitive behaviour change: upstream denies unassessed external user content; the host allows it today (epic note N5).

Paths are relative to crates/openhuman-core/src/ in tinyhumansai/openhuman at main ae18f8b769.

File	Lines	Verdict	Target	Reason
`util/url.rs`	127	KEEP	—	URL helpers stay; `host_is_local` -> tinysecurity-egress (`PrivacyCheck2`). (branch: migrated)
`security/egress/enforce.rs`	149	REIMPLEMENT	`tinysecurity-egress` `privacy_check.rs::privacy_verdict` (`PrivacyCheck2`)	`local_only_blocks` is a strict subset. Gaps E1 (upstream Sensitive denies unassessed external UserContent; host allows — behaviour change), E2 (`Metadata`/`ControlPlane` class mapping). (branch: migrated)

None.

The capability above is merged to the canonical repository's main with tests, and (for a release leaf) published with a checksum.toml.
The repository's own CI is green on Linux, macOS and Windows.
OpenHuman's matching host rows can be deleted against this release (tracked by the adoption leaf).

Files to consider: the rows above and the OpenHuman host code they replace (paths in the rows).
Research: the gaps and line references in the Change section; re-read each cited line on current main before editing, the audit is a snapshot.
Workflow: an implementing-an-epic step for Tracker: security, policy, approvals and sandboxing onto tinysecurity + tinybox (file-by-file migration epic) tinyhumansai/openhuman#8369. Follow migrate-to-submodule (bus contract only, upstream PR first, release, then digest re-pin from the published checksum.toml).
Subagent: tdd-implementer.

Merged in #19 (6d98d3d)