Simplify standalone AL code review skill (#150)

* Simplify standalone AL review skill

Rename the host-facing skill to al-code-review, reduce it to a thin Entry adapter, document the architecture, and validate host skill metadata.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: af96bb3d-893a-48a2-8298-c8f4271c162c

* Anchor plugin paths at PLUGIN_ROOT and restore the layer-filter caveat

The adapter delegated index preparation to Entry's Preparation step, but that
step is written for the clone model: it runs `pwsh ./tools/Build-KnowledgeIndex.ps1`
from the checkout root. A plugin host's working directory is the user's own
project, so the path does not resolve and the index is never built. Because
knowledge-index.json is gitignored, a fresh install has none, and READ silently
degrades to path-based discovery. The adapter now resolves Entry's repo-relative
paths against PLUGIN_ROOT and names the absolute index build; the generator
resolves its own root, so it indexes and writes the right tree from any cwd.

Entry also asserted that pruning has always happened before it runs, which is
false for an installation that ships the whole tree. Entry now scopes that
guarantee to consumers that actually prune, and the caveat dropped in the
rewrite - that enabled-layers narrows discovery rather than denying access - is
restored in the adapter and summarized in the README.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 0b67b90d-e4b4-4b92-9684-726c72c43b3f

---------

Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: af96bb3d-893a-48a2-8298-c8f4271c162c
Copilot-Session: 0b67b90d-e4b4-4b92-9684-726c72c43b3f

README.md

@@ -60,6 +60,52 @@ Skills define how agents consume knowledge. They come in three flavors:
 
 An orchestrator (such as AL-Go) points the agent at BCQuality's URL and provides a task context. The agent's first call is `/skills/entry.md`, which returns a dispatch record naming the action skill(s) to invoke. The agent then invokes each dispatched skill in turn, reading READ and DO on demand. No prior knowledge of BCQuality's structure is baked into the orchestrator — only the convention *"invoke `/skills/entry.md` first."*
 
+### Standalone plugin installation
+
+BCQuality can also be installed directly as a plugin. The plugin registers one
+host-native skill,
+[`al-code-review`](skills/al-code-review/SKILL.md), which adapts the caller's
+request to the same Entry protocol used by orchestrators.
+
+For GitHub Copilot CLI:
+
+```shell
+copilot plugin install microsoft/BCQuality
+```
+
+Plugin version `0.2.0` renamed the former `bcquality-al-review` skill to
+`al-code-review`; explicit invocations and allowlists using the old skill name
+must be updated. The name remains distinct from BC-ALAgents' public
+`al-review` skill because current hosts may load plugin skill names into one
+shared inventory.
+
+The adapter is intentionally not a second review implementation:
+
+```text
+standalone host skill: skills/al-code-review/SKILL.md
+  -> routing contract: skills/entry.md
+    -> review coordinator: microsoft/skills/review/al-code-review.md
+      -> domain review leaves
+```
+
+Only the first file follows the host's `SKILL.md` packaging format. The
+remaining files are BCQuality's internal protocol and layered action skills.
+Entry remains the single owner of routing and index preparation;
+`al-code-review.md` remains the single owner of broad-review composition. This
+separation keeps standalone installation available without duplicating those
+policies in the plugin adapter.
+
+Note that a plugin install ships the entire tree, so `BCQUALITY_ENABLED_LAYERS`
+narrows discovery without removing any files. Layer selection is a filter here,
+not a deny mechanism — see [the adapter](skills/al-code-review/SKILL.md) for the
+difference from the pruned-clone model.
+
+The host adapter and internal action skill intentionally share the
+`al-code-review` name: they expose the same operation in two different skill
+formats. Their paths make the boundary explicit. The adapter lives under
+`skills/al-code-review/SKILL.md`; the internal Microsoft-layer coordinator
+lives at `microsoft/skills/review/al-code-review.md`.
+
 ## Knowledge file format
 
 Every knowledge file is a markdown file with mandatory YAML frontmatter. Files target under 100 lines (ideal under 50). If two ideas would share a file, split them.