feat: ship native Haiku Causal Chat RC6

[bmorphism]

Outcome

This ships a native Haiku BApplication chat client plus a reproducible, rootless NATS/JetStream operator bundle. RC6 adds a privacy-safe external install/round-trip receipt so an independent Haiku user can validate the release without exposing a hostname, username, IP address, message body, or local path.

• Release: https://github.com/plurigrid/causal/releases/tag/haiku-chat-v0.4.0-rc6
• Source CI: https://github.com/plurigrid/causal/actions/runs/29895744583
• Clean Haiku VM receipt: https://github.com/plurigrid/causal/actions/runs/29895628287
• HPKG SHA-256: 61d3c961749ff5ee4ea7a48a2b5a727804f5a0fbbcce94a5e651094b8a2123de

Independent Haiku validation requested

On an x86_64 Haiku host, follow the Independent public receipt instructions, then paste only the checker stdout into a PR comment and say whether you are independent of the implementation environment. Keep stderr and the retained local evidence directory private.

The expected receipt schema is causal-haiku-external-v1; a pass binds the downloaded package digest, exact native application digest, Haiku release/architecture, public publish round trip, and exactly-once history observation. A fresh GitHub-hosted Haiku R1/beta5 VM has now produced that receipt without a source checkout. This proves a separate runtime, disk image, and network path; it is not independent human judgment.

Security boundary

The public compatibility endpoint at nonlocal.info:4222 is plaintext and is used only for a fresh non-sensitive marker. Do not send credentials or private content. Authenticated TLS/JetStream deployment is included and tested, but the current secure endpoint remains tailnet-scoped until the tailnet owner enables Funnel.

Validation

• Native x86_64 Haiku build and package metadata verified
• Anonymous GitHub asset download reproduced the published HPKG digest
• A clean GitHub-hosted Haiku VM downloaded the public assets and passed the native UI/history round trip in 44 seconds
• Clean extracted-package launch and public round trip passed on the implementation Haiku host
• Existing-window fail-closed behavior passed
• Rootless provisioner, strict NATS config, authorization roster, revocation, durable JetStream replay, pinned downloads, and secret-exclusion checks passed in CI

Known open gates

• No independent human/operator receipt has been collected yet.
• The authenticated TLS endpoint remains tailnet-only pending the owner Funnel toggle.

This PR is the public response surface for the first gate; the exact Funnel command has already been validated up to its owner-approval boundary.

[bmorphism]

Native baseline from the implementation environment (therefore not independent and not sufficient to close the external-user gate):

receipt_schema=causal-haiku-external-v1
release=haiku-chat-v0.4.0-rc6
package_sha256=61d3c961749ff5ee4ea7a48a2b5a727804f5a0fbbcce94a5e651094b8a2123de
application_sha256=6381a5af0dbcf3fba1489aede166bce915a2f28e5bcd4fbcc6ff866ab5891e43
os=Haiku
os_release=R1~beta5+development
machine=x86_64
transport=public-plaintext-nonsensitive-check-only
roundtrip=pass
history_marker_count=1
marker_sha256=97f9b81abbbe0df6cd932bcc7282b591be19168259c20bf68f7d05526e1f6fd7
local_evidence_retained=yes

An independent tester should produce the same package/application hashes and roundtrip=pass; OS release and marker hash may differ. Please paste stdout only. The evidence path printed on stderr stays private.

[bmorphism]

Clean external-runtime receipt from GitHub Actions run 29895628287. The action booted a fresh Haiku R1/beta5 VM, used no source checkout, and downloaded the public RC6 assets. This is independent infrastructure evidence, not an unaffiliated human receipt.

receipt_schema=causal-haiku-external-v1
release=haiku-chat-v0.4.0-rc6
package_sha256=61d3c961749ff5ee4ea7a48a2b5a727804f5a0fbbcce94a5e651094b8a2123de
application_sha256=6381a5af0dbcf3fba1489aede166bce915a2f28e5bcd4fbcc6ff866ab5891e43
os=Haiku
os_release=1
machine=x86_64
transport=public-plaintext-nonsensitive-check-only
roundtrip=pass
history_marker_count=1
marker_sha256=8015dbe507ddc2958a4a5a7c20a232861b31551acb4bf0b3322bf819631d0581
local_evidence_retained=yes

The next qualifying witness is a person outside the implementation environment following the linked public instructions and posting stdout only.

[bmorphism]

Latest-head replay: run 29895795213 repeated the clean Haiku VM public-release receipt at PR head f73b7ed262751daf0d76975d202ef9b781f40637 in 38 seconds. The intervening commit changed only the evidence/onboarding documentation; package and application hashes remained exact.