Build the Apple Container extension

Turns the empty scaffold into a working Nova extension for Apple Container
and container-compose, in the shape of the Docker Suite extension.

Sidebar (Scripts/Sidebar):
- System, Containers, Images, Volumes and Networks sections
- Containers grouped into compose projects via the com.docker.compose.project
  label container-compose stamps; project rows drive compose up/down/build
  against the matching workspace file
- Lifecycle, shell, logs, inspect, browse and copy commands per resource
- Apple Container publishes no event stream, so the sidebar polls while
  visible and only reloads a section when a fingerprint of its data changes,
  which keeps selection and expansion intact

Hostnames (Scripts/Hostnames.js):
- A container's hostname is <name>.<domain> and the domain lives in Apple
  Container's config.toml, which has no CLI setter, so the Hostname Domain
  preference reads and writes that file directly
- Changing it offers to register the domain with macOS and restart the
  services; the write preserves the file's other tables and its mode

Language support:
- Dockerfile and Compose syntaxes backed by tree-sitter grammars built by
  Tools/build-syntaxes.sh, pinned to revisions that generate ABI 14
- The Compose syntax is named dockercompose because that is the languageId
  docker-language-server recognises compose files by
- docker-language-server is downloaded on first use rather than bundled, at
  roughly 40 MB

Icons are generated by Tools/make-icons.py so they can be regenerated rather
than hand-maintained.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01UnSBcR5Lywz5Fbj5FmVbfc

Scripts/Sidebar/Models/Element.js

@@ -0,0 +1,30 @@
+//
+// Shared base for everything shown in the sidebar trees.
+//
+
+class Element {
+	constructor(identifier) {
+		this.identifier = identifier;
+		this.children = [];
+		this.parent = null;
+		this.expanded = false;
+	}
+
+	addChild(child) {
+		child.parent = this;
+		this.children.push(child);
+		return child;
+	}
+
+	get hasChildren() {
+		return this.children.length > 0;
+	}
+
+	// Everything about the element that should trigger a tree reload when it
+	// changes. Identity is compared separately.
+	get revision() {
+		return "";
+	}
+}
+
+module.exports = { Element };