Explain what each representative and office is responsible for

[k7lim]

Problem

The app can return representatives, but users also need plain-language context for what each office does. For example, a state senator and state representative both write laws, but represent different district sizes and sit in different chambers.

Desired behavior

• Add concise, plain-language explanations for each supported office type and government level.
• Make the explanation visible near the representative result it describes.
• Distinguish responsibilities across federal, state, county, city, school board, and other local offices as those offices become supported.
• Link to source-backed references where practical.
• Avoid implying coverage for office types that the current live provider does not return.

Notes

This lines up with docs/roadmap.md under Civics Context. It can start with state legislators because live mode currently returns state legislative offices through OpenStates.