feat(bundler): `preserveSymlinks` for monorepo workspaces with symlinked packages

[lukekania]

Goal

Honor preserveSymlinks: true so monorepo workspaces with symlinked package folders (pnpm, yarn workspaces with link protocol) resolve through the symlink rather than the canonical path.

Current state

Silently overridden — every path is canonicalized via dashmap-cached canonicalize(). This is a perf optimization but breaks scenarios where two distinct logical packages point at the same physical directory.

Scope

• crates/bundler/src/concat.rs: thread a preserve_symlinks: bool flag through BundleInput.
• Replace cached_canonicalize calls with a function that returns the input path unchanged when the flag is set.
• The npm-resolver also canonicalizes — same treatment there.

Definition of done

• A pnpm-style monorepo where two packages depend on different symlinked versions of a shared utility resolves both correctly.