Fix typecheck and pre-existing test failures

- cli/src/pre-init/tree-sitter-wasm.ts: silence TS error for the bun-only
  `with { type: 'file' }` import (TS resolves the .wasm via the package's
  exports map and has no loader for binary assets).
- cli/src/__tests__/integration-tmux.test.ts: explicitly clear
  FREEBUFF_MODE from the tmux global env before running. A prior freebuff
  build or `bun run dev:freebuff` in the same tmux server leaves it set,
  which made the help-output test see the freebuff CLI variant (no
  `--agent` flag) instead of codebuff.
- web/jest.config.cjs: fix react/react-dom moduleNameMapper paths — they
  pointed at `web/node_modules/react` but bun hoists react to the
  workspace root.
- web/jest.setup.js: polyfill TextEncoder/TextDecoder, ReadableStream,
  Request/Response/Headers/fetch from Node + undici. JSDOM lacks these
  globals, and undici (loaded transitively via `next/server`) needs them
  at module-load time.