[Feat]: As a VS Code user, I want the extension's core operations in the Command Palette so that I can create and export maps without digging through menus

[emaarco]

Summary

As a VS Code user of the Wardley Mapping Modeler, I want the extension's core operations —
creating a map and exporting the current map — available as first-class Command Palette
commands under the existing shared "Wardley" category, so that I can reach them from
Cmd/Ctrl+Shift+P without knowing about the in-canvas toolbar menu.

Motivation

The Command Palette is the primary discovery surface in VS Code. Today only the create operations
are palette commands; the export operations live solely inside the webview's canvas toolbar
menu, so a new user who wants an SVG/PNG has no way to discover them from the palette, and they
can't be bound to a keyboard shortcut. Consolidating the core operations under the existing
Wardley category makes the extension self-describing and keyboard-friendly.

What exists today — declared in apps/vscode/package.json → contributes.commands, each with
category: "Wardley". There is no contributes.menus.commandPalette restriction, so all three are
already reachable from the palette:

Command id	Title	In palette?	In file/newFile?
wardley.newMap	New Empty Map	✅	✅
wardley.newMapFromExample	New Map from Example	✅	❌
wardley.newPngMap	New Empty Map (embedded PNG)	✅	✅

What's missing — core operations that are NOT exposed as commands:

Operation	Today	Proposed command id
Export current map as SVG	webview menu only	wardley.exportSvg
Export current map as PNG	webview menu only	wardley.exportPng
(secondary) New Map from Example in File ▸ New File…	palette only	add to file/newFile menu

Proposed Solution

1. Add two new commands under the shared Wardley category:

   • wardley.exportSvg — "Export as SVG"
   • wardley.exportPng — "Export as PNG"

2. Reuse existing logic, don't duplicate. The write-to-disk half already exists in
   apps/vscode/src/exportImage.ts (exportImageToFile), and the webview already emits an export
   protocol message with the rendered data (apps/vscode/src/protocol.ts, handled in the editor
   providers WardleyEditorProvider.ts / WardleyPngEditorProvider.ts). The new commands should:

   • resolve the active Wardley editor,
   • send a new host → webview "request export" message so the webview produces the SVG text /
     base64 PNG (the same data its exportSvg() / exportPng() in src/webview/main.ts already
     produce for the in-canvas menu) — mirroring the existing requestPng round-trip used for PNG
     save,
   • pipe that into the existing exportImageToFile().

   No new export/render code — just a command entry point into the path that already runs.

3. Gate the export commands so they only appear when a map editor is focused, via
   contributes.menus.commandPalette with a when clause (e.g.
   activeCustomEditorId == 'wardley.mapEditor' || activeCustomEditorId == 'wardley.pngMapEditor'),
   so the palette isn't cluttered when no map is open. (Create commands stay ungated. Commands in
   contributes.commands get implicit onCommand activation on the engine ^1.96.)

4. (Secondary) Add wardley.newMapFromExample to the file/newFile menu for parity with the
   other two create commands.

5. Keep category: "Wardley" on every command so they group together in the palette.

Acceptance Criteria

• Wardley: Export as SVG and Wardley: Export as PNG appear in the Command Palette when a
  .wmap / .owm / .wmap.png / .owm.png editor is focused, and are hidden otherwise.
• Running either command produces the same file (with the embedded DSL) as the existing in-canvas
  export menu, via exportImageToFile — no duplicated export/render logic.
• All create + export commands share the Wardley category in the palette.
• New Map from Example is reachable from File ▸ New File… alongside the other create commands.
• npm run lint, npm test, and npm run typecheck stay green.

Alternatives Considered

• Leave export in the canvas menu only. Rejected: not discoverable from the palette and can't be
  keybound.
• A single Export… command with a Quick Pick for SVG/PNG. Viable and arguably cleaner; noted as
  an option, but two explicit commands are more directly discoverable and individually keybindable.
• Also add "Open As" convert commands (Open as Editable Text / Open as Embedded PNG via
  vscode.openWith) and an "Open Map…" picker. Deferred: VS Code's built-in Reopen Editor
  With… already converts between the editors, and file association already opens maps.
• Duplicate the export logic in a command handler. Rejected: violates reuse — exportImageToFile
  plus the existing export protocol message should stay the single source of truth.

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Note: the repo has no workspace/scope label (only enhancement, documentation, bug, refactor,
…), so this issue uses enhancement only.