Client: Upgrade TypeScript to 6.0/7.0 dual-compiler setup to match VxSuite along with additional related cleanup

[nikhilb4a]

Closes #1471

Commits

1. Upgrade TypeScript to the 6.0/7.0 dual-compiler setup, with the native 7.0 compiler as tsc.
2. Switch tsc to noEmit type-checking, since we don't use the emitted files.
3. Fix the VS Code workspace TypeScript SDK path.
4. Mark client Makefile targets .PHONY.
5. Add client lint and production-build steps to CI to catch build issues before deploy.
6. Replace the create-react-app-era react-app-env.d.ts types with vite-env.d.ts since we've moved to vite.
7. Drop @types/jspdf and @types/react-toastify, unused since those packages now ship their own types.

Update Typescript 6.0/7.0 dual-compiler setup

Upgraded to match the same Typescript setup used on VxSuite. Dual-TS version setup is standard for apps using tools like eslint, cypress, since TS7 doesn't have full API support required for those. That is expected to come in TS7.1 in late 2026/early 2027.

Install typescript 7.0.2 (native compiler) for the tsc binary and @typescript/typescript6 6.0.2 as the typescript package for tools that consume the JS API (typescript-eslint, tsserver, Cypress).

• moduleResolution "node" was removed in TS 7; switch to "bundler"
• resolvePackageJsonExports: false defers a react-hook-form v7 upgrade (v6's exports map hides its type declarations from bundler resolution)
• vite-env.d.ts satisfies TS 7's new check that side-effect CSS imports resolve (TS2882)

Why

• ~15x faster type-checking. A full tsc run on the client drops from ~30s to under 2s
  (measured on this repo). That speed shows up everywhere tsc runs:
  • every commit — the pre-commit hook type-checks via lint-staged
  • CI — test:ci runs tsc before vitest
  • local development
• Stays on the supported TypeScript line. 5.9 closed out the JS-only era of the compiler;
  new language features, lib updates, and bug fixes now ship in the 6.x/7.x lines. This keeps
  us current without waiting until an upgrade is forced by a dependency.
• Matches VxSuite's setup. Same dual-package scheme
  (typescript → @typescript/typescript6, @typescript/native → typescript@7), so both
  VotingWorks codebases follow one convention: the fast native compiler on the tsc binary,
  the behavior-matched JS compiler on the typescript package for API consumers.
• Zero tooling churn. typescript-eslint, tsserver, Vite/Vitest, and Cypress keep consuming
  the TypeScript JS API through the typescript alias — lint output is byte-identical before
  and after (0 errors, 19 warnings), and the test suite is unaffected. The bigger
  ESLint/typescript-eslint upgrade stays a separate, independent project.
• Better editor experience available. With TS 7 installed, the
  TypeScript Native Preview
  VS Code extension can run the editor language service on the native compiler too (optional;
  the default tsserver keeps working via the TS 6 package).