tests: annotate three kept bash tests with drill coverage notes

- test-worktree-native-preference.sh: drill covers PRESSURE phase only;
  RED + GREEN baselines have no drill counterpart and are kept so
  the RED-GREEN-REFACTOR validation remains rerunnable end-to-end.
- test-subagent-driven-development-integration.sh: drill covers the
  YAGNI subset (forbidden exports + reviewer-as-gate). Bash adds
  >=3 commits, >=2 subagent dispatches, TodoWrite usage, test file
  existence check, and token-budget telemetry. Kept until drill
  scenario covers those or they are retired.
- test-subagent-driven-development.sh: tests agent's ability to
  *describe* SDD (string matches against expected keywords). Drill
  scenarios test behavior, not description-recall. Kept by design.

Subagent verification recorded in commit messages of subsequent
deletions; gap analyses driving these annotations are also in the
verification subagent reports for the gating sweep.

tests/claude-code/test-subagent-driven-development.sh

@@ -1,6 +1,12 @@
 #!/usr/bin/env bash
 # Test: subagent-driven-development skill
 # Verifies that the skill is loaded and follows correct workflow
+#
+# No drill coverage: this test asks the agent to *describe* SDD (string-
+# matches its verbal explanation against expected keywords like
+# "self-review", "skeptical", "worktree", "Step 1", "loop"). Drill scenarios
+# test behavior (real subagent dispatch, plan-following, review loops),
+# not description-recall. Kept by design.
 set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"