Add project owner handoffs

[zinan92]

Summary

• add owner-thread metadata to portfolio entries and expose it in morning review
• generate durable per-project handoff prompts with exact owner-thread commands and reporting contract
• add /loop handoff facade support, docs, examples, and tests

Validation

• git diff --cached --check
• python3 -m py_compile loop-engine/bin/loopctl.py loop-engine/bin/loop_facade.py
• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 python3 -m pytest loop-engine/tests -q

Notes

This branch was rebuilt from origin/main and excludes local runtime artifacts and .loop/contract.yaml from the drifted local worktree.