chore(oxlint): enable import/newline-after-import + react/no-unstable-nested-components

oxlint 1.66 (bumped in #40318) added support for two ESLint rules that
were previously listed as not-implemented:

  - import/newline-after-import  -> enabled as "error" (3 violations,
    auto-fixed via `--fix`)
  - react/no-unstable-nested-components -> enabled as "warn" with a
    TODO to graduate to "error" after a cleanup pass (~150 violations
    that require hoisting nested component definitions out of their
    parent render functions)

Also dropped these two rules from the "not implemented in oxlint"
comment block since they are implemented now.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>