Cleanup all warnings

Achieve clean output from pnpm check, pnpm build, and pnpm lint. This parent splits the work into focused subtasks, each scoped to a confirmed group of errors.

Current Status

• pnpm check: clean (0 errors, 0 warnings)
• pnpm build: clean (prior tsconfig and :has() warnings resolved)
• pnpm lint: clean

Subtasks

• Fix cover snippet used-before-declaration — 168 errors across 84 todo pages.
• Fix pages.remote.js type errors — 5 errors (cover, sortOrder, arithmetic).
• Fix Meta.svelte type errors — 3 errors ({} not assignable to string/number).
• Fix TodoCover.svelte type errors — 2 errors (resolvedMeta fallback type).
• Fix Articles.svelte join type error — 1 error (.join on {}).
• Fix corner-shape CSS warning — 1 warning (Authors.svelte).