Add Storybook stories for Vue node components

## Context

As identified in PR #8574, we need Storybook coverage for Vue node components to prevent regressions in node styling and behavior.

## Scope

Add Storybook stories for node components in `src/renderer/extensions/vueNodes/components/`, including:

- **InputSlot.vue** - covering various states:
- Default with label
- Dot-only mode (reroute nodes with empty names)
- With/without localized names
- Different input types

- **OutputSlot.vue** - covering various states:
- Default with label
- Dot-only mode (reroute nodes with empty names)
- With/without localized names

- **Reroute nodes** - specifically testing:
- Empty string slot names (should show no labels, only connection dots)
- Interaction with NO_TITLE flag from #7589
- Minimal appearance (no 'Input 0'/'Output 0' fallback labels)

## Related

- PR #8574 - Fixes reroute node styling by hiding slot labels for empty names
- Comment: https://github.com/Comfy-Org/ComfyUI_frontend/pull/8574#discussion_r1925848362
- Requested by: @DrJKL

## Acceptance Criteria

- [ ] Stories created following ComponentName.stories.ts pattern
- [ ] Cover Default, Disabled, and relevant variant states
- [ ] Include visual regression tests for dot-only/minimal reroute appearance
- [ ] Test both explicit dotOnly prop and derived hasNoLabel behavior

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