feat!: remove HTML rendering support

[patrickkabwe]

Summary

• remove the public renderer prop and Renderer type
• delete the HTML/CSS parser, example screen, documentation, and generated renderer bindings
• keep HTML-like strings as literal text and add runtime/API contract tests

Breaking change

NitroText no longer accepts renderer="html" or renderer="plaintext", and the package no longer exports Renderer.

Verification

• bun run test -- --runInBand --no-watchman
• bun run build
• bunx nitrogen --logLevel=debug regenerated the same substantive native diff
• ./gradlew :app:assembleDebug --no-daemon --stacktrace
• npm pack --dry-run --json contains no removed renderer/parser files
• git diff --check

Local environment notes

• ESLint cannot start on main or this branch because eslint.config.mjs imports the undeclared eslint-plugin-nitro-modules package.
• The local Xcode 26.5 build stops in React Native’s CocoaPods fmt/format-inl.h consteval code before NitroText compiles. The repository CI uses Xcode 16.4.