feat(pm): show require-by chain on dependency resolution failure

[elrrrrrrr]

Summary

When ut install fails to resolve a transitive dep, the error previously showed only the failing package name — making it hard to find which of your declared dependencies pulled it in. This PR augments ResolveError with a dependency chain so the output now looks like:

ERROR Dependency resolution failed: Registry error: Failed to fetch @react-pdf/svg@^1.1.0: HTTP 404

required by:
  @lobehub/lobehub@2.1.48
  └── @react-pdf/image@3.1.0
      └── @react-pdf/svg@^1.1.0

Design

• DependencyGraph::logical_ancestry(node) walks the logical require-by chain (via resolved DependencyEdge.to), not the physical install tree. With npm hoisting the physical tree is mostly flat under root, so a physical walk would hide the real introducers.
• Built lazily on error paths only (error is already aborting resolution, so O(N+E) scan is acceptable).
• New ResolveError::WithChain { chain, source } variant, formatted in Display with a tree-style rendering that mirrors ut list.

Test plan

• cargo test -p utoo-ruborist — 160 tests pass, includes test_logical_ancestry_traces_hoisted_chain (sets up logical root→A→B→C with all three flat-hoisted physically, asserts the reported chain is [root, A, B, C]) and test_with_chain_display_renders_tree
• cargo clippy -p utoo-ruborist -p utoo-pm --all-targets -D warnings --no-deps — clean
• cargo fmt --check — clean
• Manual smoke test against a real failing install (e.g. lobehub with a 404'd dep)

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces logical dependency ancestry tracing to improve error reporting during package resolution. It adds a logical_ancestry method to the DependencyGraph to reconstruct the 'required by' chain and updates the ResolveError enum to include this chain, enabling a tree-like visualization of the dependency path in error messages. I have no feedback to provide.