The eslint-config-next ruleset surfaced 8 errors in the current
codebase. Once the CI lint job from #128 merges, every PR (including
the 0.1.2 release) would fail on these. Clearing them first so #128 can
land without breaking main.

- mcp/data.ts: 5x `any` on JSON-shaped Supabase rows → `Record<string, unknown>`.
  Matches the existing `GeneratedBrief.brief` typing right next to them
  and gives consumers an explicit narrow-required surface.
- sidebar.tsx, mobile-nav.tsx: setState-in-effect on a hydration mount
  flag. This is the canonical Next.js theme-swap pattern — SSR can't
  know resolvedTheme, so we render the light logo first and swap after
  hydration. No useEffect-free version avoids the mismatch; disable the
  rule on the setMounted line with a comment explaining the intent.
- invite/[token]/page.tsx: `Date.now()` purity error on the expiration
  check. This is a server component rendering per request, the rule
  targets client-side memoization concerns that don't apply on the
  server. Disable with a comment.

Warnings (unused imports etc.) untouched — they don't fail the build,
and addressing them is mechanical cleanup that doesn't belong in this
PR.