test(bash-lint): track 'Stage pipeline execution context' generator in REQUIRED_STEP_DISPLAY_NAMES (#1074)

pipeline.rs activates whenever on.pipeline is declared; both
pipeline-trigger-agent.md and pipeline-filter-agent.md (already in
FIXTURES) compile a step with this display name, so shellcheck already
lints its bash body.  Adding the name to REQUIRED_STEP_DISPLAY_NAMES
ensures the coverage alarm fires if the fixture is deleted or the
generator's display name changes without a corresponding update.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

tests/bash_lint_tests.rs

@@ -122,6 +122,7 @@ const REQUIRED_STEP_DISPLAY_NAMES: &[&str] = &[
     "Stage PR execution context (aw-context/pr/*)", // src/compile/extensions/exec_context/pr.rs
     "Stage workitem execution context (aw-context/workitem/*)", // src/compile/extensions/exec_context/workitem.rs (activated by PR trigger)
     "Stage manual execution context (aw-context/manual/*)", // src/compile/extensions/exec_context/manual.rs (activated by parameters: block)
+    "Stage pipeline execution context (aw-context/pipeline/*)", // src/compile/extensions/exec_context/pipeline.rs (activated by on.pipeline)
     "Resolve synthetic PR context", // src/compile/extensions/ado_script.rs synthetic_pr_step()
 ];