fix(arborist): prevent workspace bin hoisting collisions

[arjun-vegeta]

Description:
Fixes #9712

Bug:
When two workspaces each depended on a different package that exported a binary with the exact same name, Arborist hoisted both dependencies to the root node_modules/. However, because bin-links uses a "first-wins" mechanism, only one shim got created in root/node_modules/.bin/. This caused npm exec -w <loser-workspace> to fall back to the root and incorrectly execute the other workspace's binary.

Root Cause:
Because bin-links safely skips colliding binaries at the root, Arborist wasn't compensating by creating workspace-local fallbacks for the missing hoisted bin shims during the rebuild pipeline.

Fix:
Arborist's rebuild pipeline now iterates over the target's linkNodes and unconditionally creates workspace-local shims (inside packages/<workspace>/node_modules/.bin/) for every hoisted dependency that exposes a bin. Because the PATH walk-up in npm-run-script naturally prefers the local workspace .bin over the root .bin, this ensures that a workspace will always execute its specific hoisted binary correctly—bypassing the root-level collision entirely.

Testing:

• Added a regression test in test/arborist/rebuild.js that creates a monorepo with multiple workspaces and dependencies exporting conflicting my-cli binaries.
• Fails correctly without the fix. With the fix, all expected local shims are successfully written to each respective workspace/node_modules/.bin/ path and tests pass perfectly.
• All arborist tests maintain 100% line, statement, and branch coverage.