S00-018: Bound standalone XML ingress before Stanza parsing and import

Changes: Add an isolated public transport integration with finite byte, depth, element and attribute budgets; validate complete text XML with pinned saxes before real JXT parsing/import. Add adversarial and boundary fixtures, terminal cleanup tests, dependency notices and a proposed parser ADR.
Validation: Fresh-cache npm ci and npm test passed all 55 tests with Node 24.21.0/npm 11.19.0. Reproduced three stock parser failures, checked ten exact dependency licenses/integrities and 340 unchanged Stanza files; make check passed 72 tooling tests. Scope and whitespace inspected. Browser runtime, live WSS and interoperability were not tested.

Task: S00-018
Agent: auto-protocol-89fe6563092c
Role: protocol
Action: claim
Status: review

Task title: Validate bounded standalone XML ingress for the XMPP candidate

planning/TASK_MATRIX.md

@@ -1,6 +1,6 @@
 # Матрица задач
 
-Generated; state revision **43**. Canonical status: state/tasks.json.
+Generated; state revision **45**. Canonical status: state/tasks.json.
 
 | ID | Этап | Оператор | Reviewer | Статус | Owner | Зависимости | Задача |
 | --- | --- | --- | --- | --- | --- | --- | --- |
@@ -20,7 +20,7 @@ Generated; state revision **43**. Canonical status: state/tasks.json.
 | [S00-015](tasks/S00-015.md) | S00 | ci-cd | qa | done | auto-ci-cd-84e209103f24 | S00-001, S00-011, S00-013, S00-014, S00-016 | Устранить прерывание: Fix runner prompt delivery after partial stdin timeout |
 | [S00-016](tasks/S00-016.md) | S00 | ci-cd | qa | done | auto-ci-cd-351a0cbbabef | S00-001, S00-011, S00-013, S00-014 | Restore reviewer model availability after provider capacity failure |
 | [S00-017](tasks/S00-017.md) | S00 | protocol | security | done | auto-protocol-599343cd9e3f | S00-001, S00-002 | Establish fail-closed SCRAM server-final validation |
-| [S00-018](tasks/S00-018.md) | S00 | protocol | security | todo |  | S00-001, S00-002, S00-017 | Validate bounded standalone XML ingress for the XMPP candidate |
+| [S00-018](tasks/S00-018.md) | S00 | protocol | security | review | auto-protocol-89fe6563092c | S00-001, S00-002, S00-017 | Validate bounded standalone XML ingress for the XMPP candidate |
 | [S00-010](tasks/S00-010.md) | S00 | qa | orchestrator | todo |  | S00-001, S00-002, S00-003, S00-004, S00-005, S00-006, S00-007, S00-008, S00-009 | Gate: Профиль и проверка стека |
 | [S01-001](tasks/S01-001.md) | S01 | orchestrator | security | todo |  | S00-010 | Описать identity/model contracts |
 | [S01-002](tasks/S01-002.md) | S01 | orchestrator | security | todo |  | S00-010, S01-001 | Описать async account context |