Add ansible Galaxy remote type (#137)

ansible-galaxy installs pull collections straight from galaxy.ansible.com because artifactapi has no Galaxy remote type.

- add `ansible` package type proxying the Galaxy v3 API (discovery, collection versions, artifact downloads)
- forward digits-only `limit` (capped at 100) and `offset` on metadata paths, canonicalised; tarball paths forward no query
- rewrite only `href`, `download_url` and `links.*` to root-relative remote paths so tarballs flow through artifactapi
- treat `artifacts/*.tar.gz` as immutable and JSON metadata as mutable
- add `docs/ansible/remote.md`, a UI type def and an ansible e2e caching case

requires unkin/artifactapi#146

Reviewed-on: #137
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

docs/ansible/remote.md

@@ -0,0 +1,11 @@
+# `ansible` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `ansible` | Galaxy `api/` JSON (links rewritten, `limit`/`offset` forwarded) | `artifacts/*.tar.gz` |
+
+```bash
+ansible-galaxy collection install community.general -s https://artifactapi.example/api/v1/remote/galaxy/api/
+```

docs/common/caching.md

@@ -93,7 +93,7 @@ Force a moving path mutable, e.g. branch tarballs on `generic`:
 ## Built-in classification per type
 
 Each type's page lists its auto-detected mutable and immutable paths:
-[alpine](../alpine/remote.md), [alpine github](../alpine/remote-github.md),
+[alpine](../alpine/remote.md), [alpine github](../alpine/remote-github.md), [ansible](../ansible/remote.md),
 [cargo](../cargo/remote.md), [deb](../deb/remote.md), [deb github](../deb/remote-github.md),
 [docker](../docker/remote.md), [generic](../generic/remote.md), [gems](../gems/remote.md), [goproxy](../goproxy/remote.md),
 [helm](../helm/remote.md), [npm](../npm/remote.md), [nuget](../nuget/remote.md),