feat: add candidate profile intelligence

[szmyty]

What changed

• adds rights-aware portrait materialization with independent identity and reuse gates; Markey and Moulton publish pinned public-domain portraits while every unresolved candidate fails closed to initials
• adds deep-linkable candidate profiles with sourced facts, public identifiers, official/candidate-controlled links, career timelines, prior-election views, exact tables, evidence coverage, finance, provenance, and explicit gaps
• adds a disclosed closest-historical-context race transform for the U.S. Senate comparison with a shared 0–100% axis and visible non-comparability cautions
• labels seed orientation prose as AI-assisted and unreviewed
• adds portrait validation to the Pages deployment gate and documents the visualization/portrait contracts

Validation

• npm run check
• npm test
• git diff --check
• 53 tests pass; 28 portrait states validate; production Vite build passes

Review notes

• Senate career/election records are sourced but remain needs-maintainer-review in this first slice.
• Photo verification covers only portrait subject identity and reuse rights; it is not candidate, ballot, or claim verification.
• Past-election percentages are historical context, not polling or a forecast.