chore: add dev and UX story templates (#2141)

Relates to #2104

Our existing `.md` issue templates for DEV/UX stories that were added in
#2104 do not have any effect since they are only used if blank issues
are enabled which is not the case for our onyx repository. From the
[GitHub
docs](https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository#configuring-the-template-chooser):

![image](https://github.com/user-attachments/assets/a57a351f-8250-462b-8e90-6e9618a916f7)

I migrated and updated the issue templates to the new YML format.
With a recent GitHub projects update, we can then finally also use those
templates when creating new items in our [project
board](https://github.com/orgs/SchwarzIT/projects/5/views/7):

![image](https://github.com/user-attachments/assets/3ac230ef-c1f9-4439-9c65-a68afcff86ab)



Further reading:

- [Issue template
syntax](https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/syntax-for-issue-forms)

---------

Co-authored-by: Jonathan Carle <[email protected]>

.github/ISSUE_TEMPLATE/99-dev-story.yml

@@ -0,0 +1,87 @@
+name: Create a development story 📗
+description: Story template for development tasks. Exclusively used by the onyx core team for project management.
+title: "Implement|Define|Fix: ..."
+projects:
+  - SchwarzIT/5
+labels:
+  - dev
+
+body:
+  - type: textarea
+    id: description
+    attributes:
+      label: Why?
+      description: Add a short description and motivation for the story.
+    validations:
+      required: true
+
+  - type: textarea
+    id: content
+    attributes:
+      label: Content
+      description: Add, adapt and remove the following sections as necessary
+      value: >-
+        ### Open Questions/To-dos
+
+        <!-- Remove before ready -->
+
+        <!-- [ ] Add question if any, use `@` to tag people -->
+
+        ### Depends on
+
+        <!-- Add links to tickets -->
+
+        ### Design
+
+        <!-- Add Figma link and comments here -->
+
+        ### Acceptance criteria
+
+        <!--  Add ticket specific AC, e.g., the expected behavior of a component -->
+
+        ### Implementation details
+
+        <!--
+        add details if necessary, e.g.,
+        - API proposal
+        - relevant web APIs
+        - learnings from other implementations
+        - code snippets
+        -->
+
+        #### Reference implementations
+
+        <!--  add links to other frameworks and WaWi, examples:
+          - https://nuxt.com/docs/getting-started/installation
+          - https://element-plus.org/en-US/component/overview.html
+          - https://www.shadcn-vue.com/docs/components/accordion.html
+          - https://design-system.w3.org/components for structural inspiration
+        -->
+
+        #### Applicable ARIA Pattern
+
+        <!-- add link if applicable, see https://www.w3.org/WAI/ARIA/apg/patterns -->
+
+        ### Definition of Done
+
+        - The following component requirements are implemented:
+          - [ ] skeleton
+          - [ ] density
+          - [ ] example usage added to `apps/demo-app/src/views/HomeView.vue`
+        - covered by tests
+          - [ ] functional tests (Playwright or unit test)
+          - [ ] visual tests (Playwright screenshots)
+        - [ ] follow-up tickets were created if necessary
+        - [ ] updated version + documentation is deployed
+        - [ ] Storybook can show the feature
+        - [ ] Storybook code snippet of new/changed examples are checked that they are generated correctly
+        - [ ] Namings are aligned with Figma
+
+        **Approval**
+
+        - Storybook <!-- add link to deployed storybook -->
+        - Deployed Docs <!-- add link to deployed docs -->
+        - [ ] approved by designer <!-- add your @username -->
+        - [ ] approved by dev <!-- add your @username -->
+    validations:
+      required: true

.github/ISSUE_TEMPLATE/99-ux-story.yml

@@ -0,0 +1,59 @@
+name: Create a UX story 🎨
+description: Story template for design tasks. Exclusively used by the onyx core team for project management,
+title: "Concept|Adjust|Research: ..."
+projects:
+  - SchwarzIT/5
+labels:
+  - ux
+
+body:
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: Add a short description and motivation for the story.
+    validations:
+      required: true
+
+  - type: textarea
+    id: content
+    attributes:
+      label: Content
+      description: Add, adapt and remove the following sections as necessary
+      value: >-
+        ### Create "Component Name"
+
+        - [ ] _if needed_ variation
+        - [ ] density
+        - [ ] states
+        - [ ] dark mode
+        - [ ] keyboard support
+
+        ### Functions
+
+        - [ ] function 1
+        - [ ] function 2
+        - [ ] function 3
+
+        ### Figma
+
+        - [ ] dev handover
+        - [ ] ux component
+
+        ### documentation
+
+        - [ ] keyboard support
+        - [ ] property description
+        - [ ] textual documentation
+        - [ ] component grouping
+
+        ### _if needed_ links for comparison
+
+        - link 1
+        - link 2
+
+        ### Finalizing
+
+        - [ ] approved
+    validations:
+      required: true