test(suite): replace plan-label references with self-contained wording

Rust test comments/assert messages and deep-research script docstrings
cited numbered requirement labels (R3/R5) and task labels (TASK-016,
TASK-021) that are defined only in an external plan document. Reword
each to say what it means on its own: fail-safe crash guards, the
validator's fallback-capture warning, task-queue anchors.

assets/agents/deep-research/scripts/combine_findings.py

@@ -14,7 +14,7 @@ surface their collected output_key). This script lifts such findings into
 `pipeline_faults` (deduplicated, since a reflexion or feedback loop can
 re-run the map) so dead lanes surface in the report's Pipeline notes.
 
-Fail-safe (R3): on a crash (e.g. malformed GRAPH_STATE), `findings`
+Fail-safe: on a crash (e.g. malformed GRAPH_STATE), `findings`
 becomes the fault text itself and a PIPELINE-FAULT entry is recorded —
 the pipeline proceeds visibly degraded, and the human approval gate is
 the backstop. Existing faults are preserved best-effort.