fix(dialog): get_client_dialog_by_call_id returns only UAC dialogs

[tgeorge06]

Fixes #175.

Problem

get_client_dialog_by_call_id (src/dialog/dialog_layer.rs:452) is documented to return the client-side (UAC) INVITE dialogs with a Call-ID. Since the unified Dialog::Invite(InviteDialog) (0.6.0) it matches every Dialog::Invite with that Call-ID (line 456), so when both legs of a call share the Call-ID (a B2BUA or proxy that keeps it), the inbound UAS leg is returned as a client dialog.

Spec

• Doc comment (dialog_layer.rs:444): "Returns all client-side INVITE dialogs (UAC) that share the given Call-ID." In 0.5.x it returned Vec<ClientInviteDialog> and matched only Dialog::ClientInvite.
• RFC 3261 §12: the dialog id is Call-ID plus local and remote tag, and which tag is local depends on the role. A Call-ID match alone does not tell a UAC dialog from a UAS one.

Fix

The lookup also checks client_dlg.role() == TransactionRole::Client. Nothing else changes.

Contract / coverage

get_client_dialog_by_call_id(call_id) returns every INVITE dialog with role() == TransactionRole::Client and that Call-ID: early UAC dialogs (registered by do_invite / do_invite_async under their early id), confirmed ones, and every one of several UAC dialogs with that Call-ID when more than one is registered (the forking case the doc comment describes). Dialogs restored with restore_from_snapshot keep their role (Dialog::from_inner(inner.role, ..), dialog_layer.rs:497), so a restored UAC dialog is found and a restored UAS dialog is not. UAS dialogs are still found by get_dialog / match_dialog.

Other DialogLayer lookups, checked and not changed:

• get_or_create_server_subscription, get_or_create_server_publication, get_or_create_client_publication, get_or_create_client_subscription: they match their own typed Dialog variant, so the role is already part of the match.
• get_dialog, get_dialog_with, match_dialog, remove_dialog: role-agnostic by contract (they return Dialog), as in 0.5.x.
• get_or_create_server_invite, for a request with a To tag, returns whichever INVITE dialog is stored under the id derived from the request, which can be a UAC dialog. Left as is on purpose: that id is the request's Call-ID with To tag as local tag and From tag as remote tag (RFC 3261 §12.2.2), so a match on a UAC dialog means the request is an in-dialog request of that dialog (for example a re-INVITE from the callee of an outgoing call), and InviteDialog::handle handles it for both roles. Refusing it would answer 481 to a valid re-INVITE for code that sends every INVITE through get_or_create_server_invite (as src/bin/bench_ua.rs:99 does).

Behaviour change: a caller that used get_client_dialog_by_call_id to find the UAS dialog of a call no longer gets it. No caller in the repository, examples or bench_ua uses it.

Tests

src/dialog/tests/test_dialog_layer.rs:

• test_get_client_dialog_by_call_id_returns_only_uac_dialogs: one DialogLayer with an inbound INVITE answered by get_or_create_server_invite and an outbound do_invite_async with the same Call-ID. get_client_dialog_by_call_id returns exactly the UAC dialog, and the UAS dialog is still found by get_dialog.

On main (5ef8ea6) it fails:

---- dialog::tests::test_dialog_layer::test_get_client_dialog_by_call_id_returns_only_uac_dialogs stdout ----
panicked at src/dialog/tests/test_dialog_layer.rs:413:5:
assertion `left == right` failed
  left: [(Client, DialogId { call_id: "b2bua-call-id", local_tag: "G7v7MbYH", remote_tag: "" }), (Server, DialogId { call_id: "b2bua-call-id", local_tag: "zzv2h54H", remote_tag: "caller-tag" })]
 right: [(Client, DialogId { call_id: "b2bua-call-id", local_tag: "G7v7MbYH", remote_tag: "" })]

Checks

• cargo test --features bench: 386 lib tests passed, 0 failed (385 on main plus the new one), and 65 doc tests passed. Plain cargo test passes too.
• cargo check --no-default-features --features platform-embassy: no warnings, as on main.
• cargo clippy --features bench --all-targets: the same output as on main, none in the changed code. (On main it stops at a clippy::never_loop error in src/dialog/tests/test_refer_notify.rs:98, unrelated to this PR.)
• rustfmt --check on the changed files: clean.
• Merges cleanly with fix: keep confirmed dialogs confirmed on 1xx to in-dialog requests #147, fix: notify dialog state only for transitions that are applied #148 and fix(transaction): keep a server INVITE's final response after the ACK ends it #174; with all four merged all tests pass (393 lib tests).