refactor: enable built-in question tool for core agents (#302)

Adds question: allow to the permission: frontmatter of core/openagent and core/opencoder, so the OpenCode runtime permits the built-in question tool for the two interactive primary agents.

Distinct from #269, which added 'question' to the compatibility layer's ToolAccessSchema (the tools: access layer used for Claude/Windsurf translation). This is the permission: layer read by the OpenCode runtime — the two are complementary.

Verified 'question' is a first-class key in OpenCode's PermissionConfig with "allow" a valid PermissionActionConfig.

.opencode/agent/core/openagent.md

@@ -4,6 +4,7 @@ description: "Universal agent for answering queries, executing tasks, and coordi
 mode: primary
 temperature: 0.2
 permission:
+  question: "allow"
   bash:
     "*": "ask"
     "rm -rf *": "ask"

.opencode/agent/core/opencoder.md

@@ -4,6 +4,7 @@ description: "Orchestration agent for complex coding, architecture, and multi-fi
 mode: primary
 temperature: 0.1
 permission:
+  question: "allow"
   bash:
     "rm -rf *": "ask"
     "sudo *": "deny"