fix: restore Hive boundaries, mailbox delivery and CI snapshot

[DannyBaanks]

Repairing harness settings could previously reach a detached CLI launcher outside ISyCode's execution owners, and the launcher discarded the compose. This PR blocks that path at the API and UI, keeps repair tasks on the existing authorized conversation lane, and fixes the experimental Hive mailbox regressions found in the post-merge audit.

• Validate message/agent IDs and envelopes, bind senders to their outbox, reject linked paths, limit regular-file reads and preserve existing inbox messages.
• Fix inbox acknowledgement, stop replaying .sent, and let the router consult the current registry.
• Invoke the real Python coordination shim with quoted paths; reject unsupported provider hook generation rather than emitting trust-bypass configuration.
• Regenerate the M15 snapshot from the canonical generator; wait for app readiness in the intermittent compaction test.
• Redraw the activity cat as a compact orange kitten with a visible tail and stepped sleeping z marks.

Validation: 42 focused security/harness/native-import tests pass locally. The full non-integration run finished with 2,162 passed, 151 skipped and 11 deselected (767.58 s); the two isolated Hive fixes from review and their additional regression cases also pass the final 38-test Hive/cat/compaction run. Remote platform CI is pending. Textual captures at 80×24 and 180×52 confirm the disabled external-launch action and bounded activity area. Gate validator and its self-test pass without promoting any gate.

External Hive execution remains deliberately unavailable until an owner can enforce its actions. Coordination hooks are not a sandbox or an approval channel. Native Windows filesystem race resistance and live external CLI hook integration are not demonstrated by local Linux tests. See docs/audits/2026-10-18-hive-repair/GUIA.md.