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/commands/viewCommands.ts

@@ -1,8 +1,10 @@
 import * as vscode from 'vscode';
+import { isDecisionFile } from '../model/decisions';
 import { isRegistryFile } from '../model/format';
 import { isArchifyFile } from '../sources/detect';
 import { DIAGRAM_EDITOR_VIEW_TYPE } from '../views/diagramView';
 import { REGISTRY_VIEW_TYPE } from '../views/registryView';
+import { DECISION_VIEW_TYPE } from '../views/decisionView';
 import { CommandContext, isHtmlUri, openHtmlViewer, sourceUri } from './context';
 
 export function viewCommands(ctx: CommandContext): vscode.Disposable[] {
@@ -12,6 +14,7 @@ export function viewCommands(ctx: CommandContext): vscode.Disposable[] {
       if (!uri) return;
       if (isHtmlUri(uri)) return openHtmlViewer(uri);
       if (isRegistryFile(uri.path)) return vscode.commands.executeCommand('vscode.openWith', uri, REGISTRY_VIEW_TYPE);
+      if (isDecisionFile(uri.path)) return vscode.commands.executeCommand('vscode.openWith', uri, DECISION_VIEW_TYPE);
       if (isArchifyFile(uri.path)) return vscode.commands.executeCommand('vscode.openWith', uri, DIAGRAM_EDITOR_VIEW_TYPE);
       ctx.views.show(uri, vscode.window.activeTextEditor?.viewColumn ?? vscode.ViewColumn.Active);
     }),
@@ -48,9 +51,9 @@ export function viewCommands(ctx: CommandContext): vscode.Disposable[] {
         await vscode.window.showTextDocument(preview.uri, { viewColumn: column });
         return;
       }
-      const registry = ctx.registry.activeUri;
-      if (registry) {
-        await vscode.commands.executeCommand('vscode.openWith', registry, 'default', vscode.ViewColumn.Beside);
+      const page = ctx.registry.activeUri ?? ctx.decision.activeUri;
+      if (page) {
+        await vscode.commands.executeCommand('vscode.openWith', page, 'default', vscode.ViewColumn.Beside);
         return;
       }
       const html = ctx.htmlViewer.activeUri;