[codex] fix config install state and Windows installer probing

[Sunrisepeak]

Summary

• keep type=config packages repeatable when they do not create their own payload
• stop xlings from making config packages look installed via the automatic .xim-installed stamp or .xpkg.lua snapshot
• update the Windows quick installer to use only two release source families: official GitHub and GitCode xlings-res/xlings
• probe release metadata latency and prefer the lower-latency source among candidates for the selected version
• avoid exit in the Windows irm | iex installer path; failures now log and throw instead of terminating the caller PowerShell host directly

Root Cause

Config package installed state is based on install_dir being a non-empty directory. The previous behavior wrote xlings-owned content into an otherwise empty config install dir after the install hook, so a repeatable config package could be treated as already installed on the next run. The fix keeps the normal install dir setup, but skips xlings-owned installed markers/snapshots for config packages.

The Windows quick installer previously resolved and downloaded from a single GitHub URL. On query/download/extract failure it called exit 1; in the one-line irm ... | iex flow that can terminate the caller PowerShell session/window. The installer now probes GitHub and GitCode metadata latency, keeps the highest available version when no version is specified, then downloads from the lower-latency candidate for that version with fallback on download failure.

Verification

• git diff --check
• xmake build xlings
• bash tests/e2e/config_install_no_implicit_dir_test.sh
• bash tests/e2e/windows_quick_install_resource_probe_test.sh
• release-resource probes with gh release view and GitCode API checks