Rules wanted: teach Diskern about the caches on your platform

[Muawiya-contact]

The rules database is thirteen rules. That is the whole of what Diskern
knows:

chrome-cache · firefox-cache · pip-cache · rust-target · node-modules
unix-system-logs · macos-user-logs · windows-crash-logs
installer-packages · temp-dirs
windows-driverstore · windows-winsxs · windows-installer-cache

Everything else on a disk classifies as unknown, and report::build
drops those — so for most people, most of what is actually eating their
space is invisible.

This is the contribution that needs the most people and the least
Rust. A rule is JSON:

{
  "id": "npm-cache",
  "patterns": ["**/.npm/_cacache/**", "**/appdata/local/npm-cache/**"],
  "category": "package_manager_cache",
  "verdict": "safe",
  "description": "npm's download cache. Re-fetched on demand; removing it costs one slower install."
}

Things worth having, if you know where they live on your platform:

• package managers — npm/pnpm/yarn, Go module cache, Gradle, Maven, Composer, NuGet, Homebrew
• browsers — Edge, Safari, Brave, Chromium variants
• creative apps with enormous caches — Adobe, DaVinci, Blender
• IDEs — JetBrains, VS Code workspace storage, Xcode DerivedData
• containers — Docker/Podman overlay and build caches

Read docs/RULES.md first — especially the
part on why review is the safer default and why rule order is a
safety property. The important rule about rules: safe means the user
loses nothing but time. If removing it loses state, history, licences or
credentials, it is review at most.

One rule per PR is perfect. A test in rules.rs showing the path you
mean to match, and one nearby path you mean not to match, makes it
easy to accept.

crates/diskern-core/rules/base.json