Support .archify diagram files (0.2.0)

.archify files are Archify JSON diagram sources. They open as JSON,
preview with the same commands, report validation problems, and get
completion from a schema that dispatches on diagram_type. Adds a
hello.archify example and tests for detection, the dispatching schema
and the VS Code behaviour.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

README.md

@@ -1,15 +1,46 @@
 # Archify Diagram Viewer
 
-View [Archify](https://github.com/tt-a1i/archify) diagrams inside VS Code. Open a diagram's JSON source and see the interactive diagram next to it, updated as you type. Open rendered Archify HTML files in a viewer tab instead of a browser.
+View [Archify](https://github.com/tt-a1i/archify) diagrams inside VS Code. Write a diagram in a `.archify` file and see the interactive diagram next to it, updated as you type. Open rendered Archify HTML files in a viewer tab instead of a browser.
 
 This is an unofficial extension. It bundles the Archify renderer (MIT, © tt-a1i) and runs it on VS Code's own Node runtime, so nothing else needs to be installed.
 
+## Quick start
+
+1. Create a file ending in `.archify`, for example `hello.archify`:
+
+   ```json
+   {
+     "schema_version": 1,
+     "diagram_type": "architecture",
+     "meta": { "title": "Hello Archify", "output": "hello.html" },
+     "components": [
+       { "id": "browser", "type": "frontend", "label": "Browser", "pos": [40, 120], "size": [140, 60] },
+       { "id": "api", "type": "backend", "label": "API", "pos": [260, 120], "size": [140, 60] },
+       { "id": "db", "type": "database", "label": "PostgreSQL", "pos": [480, 120], "size": [140, 60] }
+     ],
+     "connections": [
+       { "from": "browser", "to": "api", "label": "HTTPS" },
+       { "from": "api", "to": "db", "label": "SQL" }
+     ]
+   }
+   ```
+
+2. Click the preview button in the editor title, or press <kbd>Cmd/Ctrl+K V</kbd>.
+
+The same file is in [examples/hello.archify](examples/hello.archify).
+
+## The `.archify` format
+
+A `.archify` file is an Archify JSON diagram source, the same JSON the Archify CLI renders. `diagram_type` selects the kind of diagram: `architecture`, `workflow`, `sequence`, `dataflow` or `lifecycle`. VS Code treats `.archify` as JSON, so you get syntax highlighting, formatting, and completion and hover from the schema for that `diagram_type`.
+
+Archify's own naming, `name.architecture.json`, `name.workflow.json` and so on, works too.
+
 ## Features
 
-- **Live preview**: for `*.architecture.json`, `*.workflow.json`, `*.sequence.json`, `*.dataflow.json` and `*.lifecycle.json` files, or any JSON with a `diagram_type`. Use the preview button in the editor title, <kbd>Cmd/Ctrl+K V</kbd> (to the side) or <kbd>Cmd/Ctrl+Shift+V</kbd>. The preview keeps the focus and route you selected (`#focus=…`, `#route=…`) when it re-renders.
+- **Live preview**: for `.archify` files, Archify's `*.architecture.json`-style files, or any JSON with a `diagram_type`. Use the preview button in the editor title, <kbd>Cmd/Ctrl+K V</kbd> (to the side) or <kbd>Cmd/Ctrl+Shift+V</kbd>. The preview keeps the focus and route you selected (`#focus=…`, `#route=…`) when it re-renders.
 - **HTML viewer**: right-click a rendered `.html` file and choose **Open in Archify Viewer**, or use *Reopen Editor With… → Archify Diagram Viewer*. For Archify HTML already open as text, a button appears in the editor title. The viewer reloads when the file changes on disk.
 - **Problems**: `archify validate` runs on the source and reports schema, layout and evidence problems at the matching JSON location.
-- **Schema help**: completion and hover documentation come from Archify's own JSON schemas.
+- **Schema help**: completion and hover documentation come from Archify's own JSON schemas. In `.archify` files, the schema follows `diagram_type`.
 - **Source links**: in source-backed diagrams, clicking a source reference opens that file and line range in the editor. If the file is not in the workspace, the web link opens instead.
 - **Export**: the diagram's own Export menu (PNG, SVG, share card, …) saves through a VS Code save dialog.
 - **Commands**: *Archify: Render to HTML File…*, *Archify: Open in Browser*, *Archify: Refresh Preview*, *Archify: Show Source*.