[codex] Fix launch preview robustness

[Abrar118]

Summary

• Make re-registering an existing local project config use a testable helper that syncs the local project name and global index together.
• Harden terminal path validation for Windows rooted and drive-prefixed paths.
• Use a full-command-line pgrep probe for gnome-terminal-server readiness checks.
• Include resolved application args in plan_launch / launch summary details, so --dry-run shows the actual app inputs, including . expanded to the project root.

Validation

• cargo test --test launch_test -> 24 passed
• cargo test -> 60 passed
• cargo clippy --all-targets -- -D warnings -> clean
• cargo fmt --check -> clean

Notes

Local .quickdev.toml changes were intentionally left out of this PR.