Move CI, dev tools, and configs from root-level scattered locations into
a
unified `dev/` directory structure. Update all references across build
scripts, documentation, and editor configurations.

Also consolidate editor config generation into build.rs for automated
synchronization of rust-analyzer settings across VS Code and Zed.

Rename package-based terminology and structures to item-based, allowing
arbitrary items with associated locations instead of only crate
packages.
Locations are now carried through report files and included in generated
reports, with the fallback to `—` removed.

Add `mingling_ci` as a standalone CI system built on Mingling 0.4.0
to validate the next version, with report collection and manifest
listing commands.