Architecture decisions: files, diagram references, views and panels

- *.archify-decision files: id (unique, words), title, status, date,
  elements, diagrams, supersedes, and prose; parsed, merged and link-checked
  in the model index; diagnostics on the file
- diagrams point at decisions with decisions: [...] on the diagram, nodes
  and edges; stripped before Archify, unknown ids reported, completion,
  hover and go-to-definition for the ids and for elements/diagrams/
  supersedes in decision files
- Decisions panel on the main.archify page; Decisions rail panel under a
  diagram (hover lights up the node or connection); decisions on element
  cards and in the element dialog; decision view for the file, with a
  lost-model note outside a model
- Archify | New Decision… command and template; editor schemas; the three
  New Model examples carry decisions; docs, changelog, 0.8.0

src/extension.ts

@@ -13,6 +13,8 @@ import { log } from './util/log';
 import { HtmlViewerProvider } from './views/htmlViewer';
 import { DiagramViewManager } from './views/diagramView';
 import { RegistryViewProvider } from './views/registryView';
+import { DecisionViewProvider } from './views/decisionView';
+import { DECISION_SELECTOR, DecisionLanguage } from './language/decisionLanguage';
 
 export function activate(context: vscode.ExtensionContext): void {
   const models = new ModelService();
@@ -21,20 +23,26 @@ export function activate(context: vscode.ExtensionContext): void {
     views: new DiagramViewManager(context, models),
     htmlViewer: new HtmlViewerProvider(context.extensionUri),
     registry: new RegistryViewProvider(models),
+    decision: new DecisionViewProvider(models),
     models,
   };
   const refs = new RefLanguage(models);
+  const decisions = new DecisionLanguage(models);
   context.subscriptions.push(
     models,
     ctx.views,
     ctx.htmlViewer,
     ctx.registry,
+    ctx.decision,
     new DiagnosticsController(context, models),
     log(),
     vscode.languages.registerCompletionItemProvider(BRAND_COMPLETION_SELECTOR, new BrandCompletionProvider(context.extensionPath), ' ', '"'),
     vscode.languages.registerCompletionItemProvider(REF_SELECTOR, refs, ' ', '"'),
     vscode.languages.registerHoverProvider(REF_SELECTOR, refs),
     vscode.languages.registerDefinitionProvider(REF_SELECTOR, refs),
+    vscode.languages.registerCompletionItemProvider(DECISION_SELECTOR, decisions, ' ', '[', ',', '"'),
+    vscode.languages.registerHoverProvider(DECISION_SELECTOR, decisions),
+    vscode.languages.registerDefinitionProvider(DECISION_SELECTOR, decisions),
     ...viewCommands(ctx),
     ...newDiagramCommands(ctx),
     ...renderCommands(ctx),