fix(ttscgraph): preserve project-relative dump paths across filesystem aliases

[mineclover]

Summary

On macOS, the same temporary project can be spelled as both /var/... and /private/var/.... ttscgraph currently compares those lexical spellings when mapping source files into dump coordinates.

Reproduction

1. Run the graph feature suite from a checkout under the macOS temporary directory.
2. Let the project root and a compiler-reported source resolve through different /var aliases.
3. Observe project files emitted outside the project-relative coordinate space.

On current master (047b464), this fails:

• test_ttscgraph_dump_keeps_node_modules_as_external_leaves
• test_ttscgraph_dump_resolves_pnpm_workspace_edges

Expected

Filesystem aliases for the same existing path produce one project-relative graph coordinate.

Actual

A source under the project is treated as a sibling outside it, so graph lookup cannot find the expected package or workspace nodes.

Proposed fix

Resolve existing absolute filesystem paths through filepath.EvalSymlinks before applying the portable TypeScript path grammar, with lexical fallback for non-existent paths and synthetic Windows or UNC fixtures. Add a real symlink regression test.