chore(secrets): dropped drive-by changes unrelated to secret placeholders

Reverted branch-side edits to spawn-policy prompts/tests, settings tab
groups, mermaid cache typing, prewalk todo gating, and packages/ai test
churn back to merge-base content; trimmed their changelog entries. These
repaired stale CI against an older main and are stale or conflicting
against current main.

packages/coding-agent/src/task/index.ts

@@ -187,7 +187,6 @@ function renderDescription(
 		agents: renderedAgents,
 		spawningDisabled,
 		defaultAgent: spawnPolicy.defaultAgent,
-		allowedAgentsText: spawnPolicy.allowedPromptText,
 		isolationEnabled,
 		applyIsolatedChanges,
 		batchEnabled,