chore(release): bootstrap mcpp 0.0.36

[Sunrisepeak]

Summary

• bump xlings to 0.4.47 and keep mcpp.toml in sync with the binary version
• require mcpp 0.0.36 in .xlings.json
• pin CI/release package index to openxlings/xim-pkgindex@fba1ce953589df609c862d0a895fc9d6ff5eb6de, which contains xim:mcpp@0.0.36
• record the follow-up from the official mcpp-index migration in .agents/docs

Context

This follows the mcpp mixed-cache fix in mcpp-community/mcpp#89 and the xim-pkgindex mirror/index update in openxlings/xim-pkgindex#261. The 0.0.36 mcpp release fixes default mcpplibs index freshness detection when other xlings index clones already exist under ~/.mcpp/registry/data.

Verification

• mcpp --version -> mcpp 0.0.36 -
• mcpp build
• target/x86_64-linux-gnu/d14fbbf7aeceb894/bin/xlings --version -> xlings 0.4.47
• git diff --check

[Sunrisepeak]

Status update:

• CI is green on all three required workflows.
  • Linux: pass, 19m35s
  • Windows: pass, 10m28s
  • macOS: pass, 7m1s
• Normal squash merge is blocked by branch protection because an approving review is required.
• Auto-merge is disabled for this repository, so this PR needs a maintainer review before it can be merged and released.