[UX] Implement watch_action_plan monitoring workflow

[StatPan]

Parent: #60
Depends on: #62, #65

Goal

Add a workflow that answers: "How should I keep tracking this legislative issue?"

This is the AssemblyMCP-native counterpart to KoreaLawMCP's action_plan, but it must stay in legislative monitoring territory rather than legal advice.

Scope

• Normalize the topic and suggest alternate keywords.
• Identify bills and committees to monitor.
• Identify meeting and plenary schedule sources to check.
• Identify report/news searches to repeat.
• Return concrete next tool calls.

Acceptance Criteria

• Output has a stable 5-step monitoring plan.
• Steps reference AssemblyMCP tool calls, not external manual instructions only.
• The tool avoids legal advice language.
• Tests cover topic with bills and topic with no matches.