detectPackageManager only checked for bun.lockb (the old binary lockfile),
missing bun.lock — the text-based format introduced in Bun v1.0. It also
only checked the immediate project directory, causing it to fall back to
npm in monorepo setups where the lock file lives at the workspace root.

Both issues together produce a confusing "npm error Invalid Version:" failure
when running vinext deploy from a Bun monorepo workspace.

Changes:
- Add bun.lock check alongside the existing bun.lockb check
- Walk up parent directories until a lock file is found (same behaviour as
  npm/pnpm/yarn when resolving workspace roots)
- Apply the same two fixes to detectPackageManagerName
- Add unit tests covering: pnpm, yarn, bun.lock, bun.lockb, npm fallback,
  monorepo root traversal, and closest-wins precedence

Node.js fs/promises.glob requires options.exclude to be a function.
Passing an array throws TypeError on Node.js v23 and was never correct
per the API spec (introduced in Node.js v22).

PR cloudflare#52 migrated both routers from the glob npm package to the built-in
but accidentally left array literals in the exclude option for both
app-router.ts and pages-router.ts.

Changes:
- app-router.ts: `exclude: ["**/@*"]` → function that returns true when
  the entry's basename starts with "@"
- pages-router.ts: `exclude: ["api", "**/_*"]` → function that returns
  true when the entry's basename is "api" or starts with "_"

Behaviour is identical — parallel slot directories (@slot) and private
pages (_app, _document, etc.) are still excluded from route scanning.

In monorepos, packages are hoisted to the workspace root's node_modules
rather than installed in each app's own node_modules. vinext was checking
for @cloudflare/vite-plugin, @vitejs/plugin-rsc, wrangler, and @mdx-js/rollup
only in the immediate {root}/node_modules, causing false negatives for all of
them and an ENOENT crash in runWranglerDeploy when the binary was only
present at the workspace root.

Changes:
- Add findInNodeModules(start, subPath) helper to utils/project.ts that
  walks up parent directories until it finds node_modules/{subPath},
  mirroring the same approach used for lock file detection
- Use it in detectProject for hasCloudflarePlugin, hasRscPlugin, hasWrangler
- Use it in getMissingDeps for hasMdxRollup
- Use it in runWranglerDeploy to locate the wrangler binary

Add unit tests covering: direct lookup, binary lookup, null fallback,
monorepo root traversal, and closest-wins precedence.