fix(runtime): pass absolute worker RPC storage path

[dadachann]

Summary

• resolve installation-private RPC transfer storage to an absolute path before crossing into the worker process
• prevent the worker CWD from rebasing a relative default store path beneath the immutable artifact tree
• add a regression using the default relative artifact-store base and a distinct artifact CWD

Verification

• RED: new regression failed because the launcher emitted data/plugin-runtime/installations/.../rpc-transfer
• GREEN: focused launcher tests passed
• full SDK suite: 1153 passed
• Ruff and git diff --check passed

Follow-up to #117.

[dadachann]

recheck

[dadachann]

recheck