feat(i18n): author the Spanish (es) public.ftl catalog (~247 keys)

What + why

Follow-up to epic &60 (closed) Phase 3 (P3.2 ships en-only machinery; the repo has no es/ catalog). Author the Spanish translations so the machinery serves a second language.

Acceptance criteria

• An es public.ftl (~247 report-*/public-* keys) + the edge intake.ftl keys.
• ?lang=es flips the rendered public form; bilingual-coverage passes.
• Translations reviewed for child-welfare domain accuracy.

Gated on P3.1/P3.2. Tracked follow-up, not a Phase-3 child.