fix(scripts): launch vite through entrypoint on Windows

[DavidBabinec]

What changed

• Add viteCommand(...), which runs Vite by calling the current Bun executable with node_modules/vite/bin/vite.js directly.
• Switch scripts/dev.ts and scripts/e2e-dev.ts from bun run dev:vite to viteCommand(...).
• Add scripts/vite.ts as the package-script wrapper for Vite commands.
• Change dev:vite, build, and preview so package scripts no longer invoke bare vite.
• Extend devWorkflow.test.ts to assert the direct Vite entrypoint path and reject bunRunCommand('dev:vite') / bare vite launcher regressions.

Why

PR #193 fixed direct Windows uv_spawn failures, but the follow-up user report showed another lookup layer still failing:

$ vite --host "127.0.0.1" --port "5173" --strictPort
bun: command not found: vite
error: script "dev:vite" exited with code 1

That means bun run dev:vite still asks Bun's package-script runner to resolve the bare vite command on that Windows setup. This PR removes that lookup path entirely for bun run dev: the child process is now process.execPath plus Vite's JS entrypoint path.

Verification

• Red-green regression: bun test src/__tests__/devWorkflow.test.ts failed before the helper/wrapper existed, then passed after the fix.
• bun -e "import { viteCommand } from './scripts/lib/bunCommand.ts'; const r = Bun.spawnSync(viteCommand('--version'), { stdout: 'pipe', stderr: 'pipe' }); console.log('exit', r.exitCode); console.log(r.stdout.toString().trim()); console.error(r.stderr.toString().trim()); process.exit(r.exitCode ?? 1);"
• bun run scripts/vite.ts --version
• bun run dev:vite --version
• bun run build
• bun run lint
• bun test → 6024 pass, 0 fail
• PORT=3091 VITE_PORT=5191 bun run dev smoke: CMS listened on 3091, Vite reported ready on 5191, no command not found, Script not found, uv_spawn, or ENOENT output.