Attribution format is consistent across response types

Ad-hoc citation language — sometimes [1], sometimes "according to the docs," sometimes nothing — prevents the UI from rendering clickable references, breaks footnote components, and forces users to scroll back and hunt for sources. This degrades the user-experience taxon and undermines the inference-contract: users cannot verify claims when citations are inconsistent or absent. Support teams cannot build tooling on top of an undefined format, and audit trails for regulated industries become unworkable.

Define a single citation format in the system prompt (inline numbered brackets plus a trailing reference list) and add matching UI components to render the markers as clickable footnotes. Update the prompt in lib/ai/prompts.ts and the renderer in components/ai/citations.tsx.

const systemPrompt = `Cite inline with [1], [2]. End with: [1] Title — section, [2] Title — section.`