Add package build tool definitions

[abhinavgautam01]

Closes #146

Summary

• Add build-tool definitions for Conda Build, Arch Linux Packaging, Debian Packaging and FreeBSD pkg.
• Detect Conda recipes through meta.yaml, meta.yml and legacy/v1 recipe/ layouts.
• Detect Arch package metadata through .SRCINFO, .AURINFO and .PKGINFO.
• Detect Debian packaging through debian/control and *.dsc.
• Detect FreeBSD package metadata through +COMPACT_MANIFEST.
• Keep generated package metadata as detection-only signals rather than editable configuration.
• Add focused fixtures and signal-level regression tests for every definition.
• Regenerate the README tool inventory.

Testing

• go build ./...
• go test -race ./...
• golangci-lint run ./...
• git diff --check
• Verified the README tools block matches generated output.

[andrew]

Thanks — this matches the issue file-list closely and the tests cover each signal on all three platforms.

One thing before merge:

knowledge/_shared/conda-build.toml detects recipe/recipe.yaml / recipe/recipe.yml, which is the CEP-13 v1 recipe format. conda-build itself cannot read that format — only rattler-build can — so a repo whose only signal is recipe/recipe.yaml (the fixture in this PR) is reported with run = "conda-build .", which fails against that file. Please add "rattler-build build" to commands.alternatives.

[abhinavgautam01]

Thanks, Fixed. rattler-build build is now offered for CEP-13 v1 recipes, with a regression test covering the v1 fixture.

[andrew]

Thanks — rattler-build alternative and test look good.