Add BPMN editor extension

[rlfnb]

Adds a new web-app-bpmn extension that enables creating, opening and editing BPMN 2.0 process diagrams (.bpmn files) directly in OpenCloud Web.

The extension embeds https://bpmn.io/toolkit/bpmn-js/ as a native Vue component (no iframe) and includes:

• Modeler with full toolbar/palette for editing diagrams
• Properties Panel (right sidebar) for editing element attributes like names, conditions, etc.
• Viewer mode for read-only access
• New file menu integration — users can create new .bpmn diagrams from the file manager
• Autosave — changes are emitted on every command stack change

Architecture follows the same pattern as the existing web-app-draw-io extension.

Related Issue

• n/a (new feature)

How Has This Been Tested?

• test environment: Node v22, pnpm 11.9, Vitest, vue-tsc
• test case 1: pnpm --filter bpmn test:unit — 3 unit tests passing (canvas rendering, properties panel visibility in edit/readonly mode)
• test case 2: pnpm --filter bpmn check:types — no type errors
• test case 3: pnpm --filter bpmn build — production build successful
• test case 4: Manual verification via docker-compose up with volume mount to /web/apps/bpmn

Types of changes

• Enhancement (a change that doesn't break existing code or deployments)

[dschmidt]

Mind to add a few screenshots to the PR?

Havent looked in detail, but it looks pretty solid from afar!

One nitpick: would you mind porting the vue component to the script setup syntax?

[rlfnb]

some low hanging fruits added to the bpmn app, feel free to squash them into one commit, if you want it as one commit. Also find a screenshot below (added a podman dev setup as well as a bonus for it).