New Features:
- Added `MessageKind::SipInvite { direction, profile, call_id }` variant
for sofia "receiving invite" / "sending invite" log lines. Sofia emits
these for every inbound and outbound call regardless of dialplan,
making them the canonical primitive for `sip_call_id ↔ channel_uuid`
correlation. Consumers no longer need to substring-search inside
`ChannelLifecycle.detail`. The `(null)` outbound case and the version-
only DEBUG follow-up from `sofia_glue.c:1676` both yield `call_id: None`.
- Added `SipInviteDirection` enum (`Receiving`, `Sending`), re-exported
from the crate root. Marked `#[non_exhaustive]`.
API Changes:
- `MessageKind` gained one variant. Already `#[non_exhaustive]` so this
is not a breaking change for downstream `match` arms — patch-level
bump under Cargo's pre-1.0 semver rules.
- `MessageKind::ALL_LABELS` gained `"sip-invite"`.
Packaging:
- Explicitly exclude `tests/fixtures/` and `tests/production_log.rs`
from the published crate. The fixtures were already absent (gitignored)
but the test file referencing them was being shipped, leaving consumers
with a `cargo test` that couldn't find its data files.