feat(acp): move claude-agent-acp to 0.73.0 and codex-acp to 1.8.0

codex-acp 1.8.0's initialize response differs from 1.7.0's by exactly one
field, `sessionCapabilities.fork: {}`, so codex sessions gain the fork entry
point on the pin alone. Both adapters also publish AI-generated session
titles through `session_info_update.title`, the channel `acp::session_title`
already consumes.

claude-agent-acp 0.73.0 rebuilt its permission layer the way codex did in
1.7.0: option-level `_meta.permission.changes[]` is gone and the only `_meta`
left is the request-level `{version, title, description?}` block that
`hoist_request_permission_meta` already carries onto the card. The per-option
scope chip is lost with it, which is accepted — the option name now spells out
both the grant and its duration. `parsePermissionOptionChanges` stays for
users pinned to an older adapter.

Its new native subagent and async-task channels remain off: both are gated on
client advertisements codeg does not make.

Also correct four comments the two releases invalidated.